The internet is the world’s largest communication network. It connects computers, phones, servers, data centers, satellites, and countless other devices, allowing them to exchange information across enormous distances.
When you open a website, send a message, stream a movie, make a video call, play an online game, or upload a photo, you are using the internet. Yet the internet itself is not one giant machine sitting in a particular place. It is a vast collection of interconnected networks that agree to communicate using common technical standards.
That simple idea has grown into infrastructure that supports modern communication, business, education, entertainment, science, government services, and much of everyday life.
Understanding how the internet works becomes easier once you separate a few ideas that are often mixed together. The internet is the underlying network infrastructure. The World Wide Web is one service that runs on that infrastructure. Websites, email, streaming platforms, messaging apps, online games, cloud services, and many other applications use the internet in different ways.
What exactly is the internet?
The internet is a global network of networks.
A home network might connect your phone, laptop, television, and other devices to a router. Your router connects to your internet service provider, or ISP. The ISP connects to larger networks, which connect to other networks operated by telecommunications companies, cloud providers, universities, governments, businesses, and other organizations.
These networks can exchange data because they use shared communication protocols.
There is no single company that owns the entire internet. Different organizations own and operate different pieces of the infrastructure, while technical standards allow those pieces to work together.
This decentralized structure is one of the internet’s defining characteristics.
Internet vs. World Wide Web
The terms “internet” and “web” are often used interchangeably, but they mean different things.
The internet is the underlying global network infrastructure.
The World Wide Web is a system of interlinked documents and resources that people access over the internet, primarily through web browsers.
The web uses technologies such as HTTP, HTTPS, HTML, CSS, and JavaScript.
But the web is only one part of the internet.
Email, online gaming, file transfers, voice calls, video conferencing, cloud applications, and many other services can use the internet without being ordinary web pages.
A useful analogy is a transportation system. The internet is like the network of roads and other infrastructure, while the web is one type of service that uses those roads.
How did the internet begin?
The internet developed over several decades rather than appearing as a finished invention.
One important early project was ARPANET, a computer network developed with funding from the U.S. Department of Defense’s Advanced Research Projects Agency, later known as DARPA.
ARPANET connected computers at research institutions and universities and helped demonstrate the practical value of packet-switched networking.
In traditional telephone communication, a dedicated connection could be established between two endpoints. Packet switching took a different approach: information could be divided into smaller pieces called packets, which could travel through a network and be reassembled at their destination.
ARPANET was not the modern internet by itself. It was one of the important foundations from which today’s interconnected networks developed.
The development of TCP/IP
A major milestone came with the development and adoption of the Transmission Control Protocol/Internet Protocol, commonly called TCP/IP.
TCP/IP provided a standardized way for different networks and computers to communicate.
IP handles addressing and routing packets between networks. TCP provides mechanisms for reliable delivery and organizing data into a coherent stream for applications that need it.
On January 1, 1983, ARPANET officially switched to TCP/IP, an event often regarded as an important milestone in the development of the modern internet.
The significance of TCP/IP was not simply that it connected individual computers. It provided a common language that allowed separate networks to interconnect.
The World Wide Web arrives
The web came later.
In 1989, British computer scientist Tim Berners-Lee proposed a system for sharing information over the internet using hypertext. He developed the foundational technologies of the World Wide Web, including HTML, HTTP, and the first web browser and web server.
The first website went online around 1990.
The web made it much easier for people to navigate between information resources through hyperlinks. As browsers became more capable and internet access spread, the web became one of the most visible parts of the internet.
How does the internet actually work?
At its simplest, the internet works by moving data between devices.
Suppose you enter a website address into your browser.
Your computer or phone needs to determine where that website is hosted. It then sends requests through a series of networks toward the appropriate server. The server processes the request and sends data back.
That description hides a remarkable amount of engineering.
The information is broken into packets. Routers examine packet addresses and determine where to send them next. Different packets can potentially take different routes through the network before reaching their destination.
Your device then receives the data and the appropriate software reconstructs it into something you can see or hear.
What are packets?
Data traveling across the internet is commonly divided into smaller units called packets.
Imagine sending a large book through a delivery system. Instead of placing the entire book into one enormous container, you could divide it into many numbered packages.
Each package would contain information about where it came from, where it is going, and how it fits into the larger shipment.
Internet packets work on a similar principle.
Breaking data into packets makes networks more flexible and efficient. Network equipment can handle many streams of communication simultaneously instead of maintaining one dedicated physical path for every conversation.
Different protocols determine exactly how packets are structured, transmitted, routed, checked, and reassembled.
What is an IP address?
Every device communicating over an IP network needs an address that allows traffic to be delivered to the appropriate destination.
An IP address is a numerical identifier used by the Internet Protocol.
There are two major versions in widespread use:
- IPv4, which uses 32-bit addresses
- IPv6, which uses 128-bit addresses
An IPv4 address looks like:
192.0.2.1
An IPv6 address is much longer and uses hexadecimal notation, such as:
2001:db8::1
IPv6 was developed partly because the world has far more internet-connected devices than the original IPv4 address space can comfortably accommodate.
Network technologies such as address translation have helped extend the useful life of IPv4, but the long-term expansion of internet connectivity depends heavily on IPv6.
What is DNS?
People prefer names such as example.com rather than remembering numerical IP addresses.
The Domain Name System, or DNS, translates domain names into information that computers can use to locate network resources.
When you type a domain name into a browser, your device generally needs to perform a DNS lookup.
A simplified version of the process looks like this:
- You enter a domain name.
- Your device asks a DNS resolver for information about that domain.
- The DNS system finds the relevant records.
- Your device learns the appropriate IP address or other destination information.
- The browser can then communicate with the appropriate server.
DNS is often described as the internet’s phone book, although the modern system is considerably more sophisticated than a simple list of names and numbers.
What happens when you visit a website?
Opening a website involves several steps that normally happen in fractions of a second.
First, the browser determines which server it needs to contact, often using DNS.
It then establishes network communication with the destination. If the site uses HTTPS, the browser and server also establish an encrypted connection using modern security protocols.
The browser sends an HTTP request asking for a resource.
The server receives the request and sends an HTTP response.
That response may contain HTML, which tells the browser about the structure of the page. The browser can then request additional resources such as images, stylesheets, fonts, scripts, and videos.
The browser processes those resources and constructs the page displayed on your screen.
A modern website can therefore involve communication with many different servers and services before the page is fully loaded.
What is a web server?
A server is a computer system that provides services or resources to other computers.
A web server specifically handles web requests and delivers web content or data.
A server can be a physical machine, but modern internet services frequently use virtual machines, containers, distributed systems, and cloud infrastructure.
Large websites may not depend on one physical computer at all. They can operate across many servers and data centers distributed around the world.
This allows services to handle enormous numbers of users and continue operating even when individual machines fail.
What is a data center?
A data center is a facility containing computing and networking equipment.
Large data centers can contain thousands of servers, along with systems for power, cooling, physical security, networking, storage, and monitoring.
Cloud computing companies operate enormous data-center networks that provide computing resources to businesses, governments, developers, researchers, and consumers.
When you use an online service, your data may be processed in a data center that is physically far away from you.
The internet makes that distance largely invisible to the user.
How does information travel across the world?
Internet traffic can travel through many different physical systems.
Long-distance communication relies heavily on fiber-optic cables, including submarine cables crossing oceans.
Fiber-optic cables transmit information using pulses of light through extremely thin strands of glass or other material.
The cables themselves can be surprisingly thin compared with the amount of information they can carry.
Submarine cables are particularly important because they connect continents and carry enormous volumes of international internet traffic.
Despite the wireless appearance of modern internet use, much of the world’s long-distance digital communication ultimately depends on physical cables.
How does Wi-Fi fit into the internet?
Wi-Fi is not the internet itself.
Wi-Fi is a wireless networking technology that allows devices to communicate with a local network using radio waves.
In a typical home setup, your phone or laptop connects wirelessly to a Wi-Fi router. The router then connects to your ISP through a separate connection, such as fiber, cable, DSL, or another access technology.
So when you connect to Wi-Fi, you are usually connecting first to a local network that provides a pathway to the internet.
A device can also use the internet without Wi-Fi, such as through a cellular network or a wired Ethernet connection.
How does cellular internet work?
Smartphones can access the internet through cellular networks.
A phone communicates wirelessly with a nearby cellular base station. The carrier’s network then transports that traffic toward its destination.
Modern cellular networks use technologies such as 4G LTE and 5G.
5G is not simply “faster Wi-Fi.” It is a cellular networking technology designed to support higher data rates, lower latency in some circumstances, greater device density, and other capabilities depending on the network configuration and frequency bands being used.
The actual performance experienced by a user depends on factors such as signal conditions, spectrum, network congestion, device capabilities, and the carrier’s infrastructure.
What is bandwidth?
Bandwidth describes the amount of data that a network connection can theoretically carry over a given period, commonly expressed in bits per second.
For example:
- 1,000 bits per second = 1 kilobit per second
- 1 million bits per second = 1 megabit per second
- 1 billion bits per second = 1 gigabit per second
Internet plans are commonly advertised using megabits or gigabits per second.
Bandwidth is not the same thing as speed in every practical sense, however.
A connection with high bandwidth can carry a large amount of data, but the experience of loading a website or playing an online game also depends on latency, congestion, server performance, routing, and other factors.
What is latency?
Latency is the time it takes for data to travel between endpoints or for a network operation to receive a response.
High bandwidth is useful when transferring large amounts of data, such as downloading a video.
Low latency is particularly important for applications that require rapid interaction, such as online gaming, video calls, remote control systems, and some financial or industrial applications.
Distance matters because information cannot travel faster than the physical limits imposed by nature. Network equipment and routing also introduce additional delays.
A fast connection can therefore still have noticeable latency when communicating with a distant server.
Why does internet service sometimes feel slow?
Internet performance depends on much more than the advertised connection speed.
Possible bottlenecks include:
- Congestion on the local network
- Weak wireless signals
- Problems with the ISP
- Overloaded network equipment
- Long or inefficient routes
- Busy servers
- Slow databases or application software
- Large files or poorly optimized websites
- Problems in the user’s device
A website can therefore load slowly even when the user’s internet connection has substantial bandwidth.
What is a router?
A router is a networking device that forwards data between different networks.
Your home router commonly performs several jobs at once. It can connect your local devices to your ISP, provide Wi-Fi, assign local addresses, and manage traffic between your home network and the wider internet.
Large networks also use routers, but those devices can be vastly more powerful and sophisticated.
Routers examine packet information and use routing tables and protocols to determine where traffic should go next.
How do internet providers connect to one another?
The internet depends on networks exchanging traffic with other networks.
One important concept is peering, in which networks exchange traffic directly.
Networks can also purchase transit from other networks that provide connectivity to destinations they cannot reach directly.
Large networks that connect many other networks are sometimes described as Tier 1 networks, although the exact classification is based on how they obtain connectivity rather than simply their size.
This interconnected structure helps create a global network without requiring one central organization to route every packet.
What is an autonomous system?
Large networks participating in internet routing can operate as autonomous systems, commonly called ASes.
An autonomous system is a collection of IP networks and routers under a common administrative policy.
Each autonomous system is identified by an Autonomous System Number, or ASN.
Networks exchange routing information using protocols such as BGP, the Border Gateway Protocol.
BGP is one of the technologies that allows the enormous collection of independently operated networks making up the internet to exchange information about reachable destinations.
What is BGP?
The Border Gateway Protocol helps networks determine how to reach IP address ranges through other networks.
Unlike a simple map showing one fixed route between every destination, internet routing involves policies, relationships, costs, redundancy, and constantly changing network conditions.
BGP allows networks to advertise routes and select among available paths.
Because BGP plays such a central role in global connectivity, configuration mistakes or malicious manipulation can sometimes cause large-scale routing problems.
What is HTTPS?
HTTPS stands for Hypertext Transfer Protocol Secure.
It is HTTP transmitted through a secure cryptographic connection, normally using TLS, or Transport Layer Security.
HTTPS helps protect information exchanged between your browser and a website from being read or altered by third parties on the network.
It also allows the browser to authenticate the server through digital certificates.
HTTPS does not mean that everything a website does is automatically safe or trustworthy. A malicious or fraudulent website can also use HTTPS.
The technology primarily protects the communication channel and helps establish the identity of the server.
What is encryption?
Encryption transforms information into a form that is difficult for unauthorized parties to understand.
Modern internet security relies heavily on cryptographic techniques.
When you visit an HTTPS website, encryption helps protect the information traveling between your device and the website.
Different applications can use different forms of encryption. End-to-end encrypted messaging, for example, is designed so that the communicating users—not merely the network connection—control access to the message contents.
Encryption is one of the fundamental technologies that makes private digital communication possible.
What is a firewall?
A firewall is a security system that controls network traffic according to defined rules.
Firewalls can exist on individual computers, home routers, corporate networks, cloud infrastructure, and other systems.
They can block unwanted connections, restrict access to particular services, and help reduce exposure to attacks.
A firewall is only one layer of cybersecurity. It does not by itself protect a system from every type of threat.
What are cookies?
A cookie is a small piece of information that a website can store in a user’s browser.
Cookies can serve useful purposes, such as keeping a user signed in, remembering preferences, maintaining shopping carts, and supporting certain website functions.
They can also be used for tracking and advertising-related purposes.
Modern browsers provide controls for managing cookies, although privacy behavior varies between browsers and websites.
Cookies are only one part of the broader ecosystem of web tracking technologies.
What is cloud computing?
The cloud is not a mysterious place where data floats.
Cloud computing generally means using computing resources—such as servers, storage, databases, and software—over a network, often through large commercial data centers.
Instead of running everything on your own computer, you can use remote computing resources operated by another organization.
Examples include online file storage, web-based applications, streaming services, hosted databases, and computing platforms used by software developers.
Cloud services can make computing resources easier to scale, but they also create dependencies on providers, networks, and data-center infrastructure.
How does video streaming work?
When you stream a movie or video, your device receives a sequence of data over the internet rather than necessarily downloading the entire file before playback begins.
Streaming services commonly store copies of content on servers distributed geographically.
They may use content delivery networks, or CDNs, to place frequently requested content closer to users.
Your device receives data in chunks and maintains a buffer to help keep playback smooth.
If network conditions deteriorate significantly, the service may reduce video quality or pause while more data is received.
What is a content delivery network?
A content delivery network, or CDN, is a distributed system of servers designed to deliver web content and other digital resources efficiently.
Instead of requiring every user to retrieve a file from one central server, a CDN can store copies at multiple locations.
When you request an image, video, webpage resource, or other cached content, the system may serve it from a location relatively close to you.
This can reduce latency, lower the load on an origin server, and improve reliability.
How does email travel over the internet?
Email uses several protocols rather than a single system.
When you send an email, your mail application communicates with a mail server. The sending server can use SMTP, the Simple Mail Transfer Protocol, to transfer the message toward the recipient’s mail provider.
The recipient can then access the message using systems such as IMAP or web-based interfaces.
The message may pass through multiple servers and security systems before reaching its destination.
Email therefore illustrates an important feature of the internet: different organizations can operate separate services while still communicating through standardized protocols.
What is an internet protocol?
A protocol is a set of rules governing communication between systems.
Internet protocols specify things such as how data is formatted, addressed, transmitted, received, and interpreted.
Important examples include:
- IP for addressing and routing
- TCP for reliable data transmission
- UDP for lightweight datagram-based communication
- HTTP for web communication
- HTTPS for secure HTTP
- DNS for translating domain names into network information
- SMTP for sending email
No single protocol does everything. The internet works because many protocols operate together in layers.
Why is the internet designed in layers?
Internet communication is easier to develop and maintain when different responsibilities are separated.
One layer can focus on moving packets between networks. Another can handle reliable transmission. Another can define how an application communicates.
This layered approach means an application does not need to know every detail about the physical network carrying its data.
For example, a web browser can use HTTP without needing to know whether the underlying connection uses fiber, Wi-Fi, Ethernet, or cellular technology.
The layers cooperate through standardized interfaces.
Who controls the internet?
No single government, company, or organization controls the entire internet.
Different entities control different parts.
Telecommunications companies operate networks. Cloud companies operate data centers. Universities operate networks. Governments operate infrastructure and regulate internet activity within their jurisdictions. Businesses operate websites and online services.
Technical coordination also matters.
Organizations such as the Internet Corporation for Assigned Names and Numbers (ICANN) coordinate important aspects of domain names and Internet number resources. The Internet Engineering Task Force (IETF) develops and maintains many of the technical standards used by internet systems.
The result is a system based on distributed ownership combined with shared standards and coordination.
How are domain names organized?
Domain names are hierarchical.
Consider:
www.example.com
The rightmost portion, .com, is a top-level domain, or TLD.
example is the domain name within that TLD.
www is a subdomain or host name.
The DNS hierarchy allows the enormous collection of domain names to be organized into a distributed system.
There are many generic top-level domains, such as .com, .org, and .net, along with country-code top-level domains such as .uk, .jp, and .bd.
What is an internet exchange point?
An internet exchange point, or IXP, is a physical location where different networks can connect and exchange internet traffic.
Instead of sending traffic through an intermediary network, two participating networks can sometimes exchange traffic directly through an exchange.
This can reduce costs and improve routing efficiency.
Large internet exchange points can connect many networks in the same facility, creating important hubs in the global internet infrastructure.
How does the internet stay reliable?
The internet is designed with substantial redundancy.
Traffic can often take different paths between locations. Networks can have multiple connections to other networks, and large services can operate servers in multiple data centers.
If one route or machine fails, traffic may be rerouted or services may continue operating elsewhere.
This does not make the internet immune to outages.
Undersea cable damage, power failures, equipment problems, software mistakes, cyberattacks, natural disasters, and routing errors can all disrupt connectivity.
But the decentralized nature of the network means a failure in one location does not normally shut down the entire internet.
What happens when an undersea cable breaks?
Because so much international traffic travels through submarine fiber-optic cables, cable damage can affect internet connectivity.
Ships, anchors, fishing activity, earthquakes, and other events can damage cables.
Networks may reroute traffic through other cables, but available alternatives may have limited capacity or take longer routes.
Cable repair requires specialized ships and equipment and can take time.
This is one reason the physical infrastructure of the internet matters just as much as the software people see on their screens.
Is satellite internet really wireless?
Yes, but the broader internet still depends on physical infrastructure somewhere along the route.
Satellite internet connects a user’s equipment to satellites rather than requiring a conventional terrestrial last-mile cable or cellular tower.
The satellite then communicates with ground infrastructure that connects into the wider internet.
Satellite systems can provide connectivity in places where building terrestrial networks is difficult or expensive.
Their performance depends on factors including satellite orbit, network architecture, weather conditions for some frequency bands, ground infrastructure, and the service’s capacity.
What is the difference between the dark web and the deep web?
The deep web refers broadly to online content that ordinary search engines do not index.
That includes many completely ordinary things: private email accounts, online banking pages, subscription databases, private company systems, and content behind login screens.
The dark web is a smaller portion of the internet that requires specialized software or configurations to access and is intentionally designed to provide additional anonymity or concealment.
The two terms are therefore not interchangeable.
Most of the deep web is mundane private or restricted information rather than something sinister.
What is an internet search engine?
A search engine is a service that helps users find information across the web.
Search engines generally discover pages through automated systems, process and index information about those pages, and then use ranking systems to determine which results are most relevant to a user’s query.
Search engines do not contain the entire internet.
They primarily index content they can discover and access, while private, blocked, unlinked, or otherwise inaccessible content may not appear in search results.
How does internet advertising work?
Online advertising involves a complex ecosystem connecting advertisers, publishers, platforms, data systems, and users.
An advertisement can be selected based on factors such as the page being viewed, broad audience characteristics, contextual information, or information used for personalization, depending on the service and the user’s privacy settings.
Advertising helps finance many free online services, including websites, search engines, social platforms, and applications.
At the same time, online advertising raises questions about privacy, tracking, transparency, competition, and control over personal data.
What are internet service providers?
An internet service provider, or ISP, is an organization that provides customers with internet connectivity.
ISPs can use different access technologies, including:
- Fiber-optic connections
- Cable broadband
- DSL
- Fixed wireless
- Mobile cellular networks
- Satellite connections
The technology available to a customer depends heavily on location and infrastructure.
An ISP typically connects the customer’s local network to the broader collection of networks that makes up the internet.
What is net neutrality?
Net neutrality is the principle that internet service providers should treat internet traffic according to rules that prevent certain forms of discriminatory treatment, such as blocking or improperly throttling particular online services.
The policy debate around net neutrality involves questions about competition, consumer protection, network management, investment, free expression, and the authority of regulators.
Different countries and jurisdictions have adopted different rules, and policies can change over time.
What is the digital divide?
Not everyone has the same access to the internet.
The digital divide describes differences in access to internet connectivity, devices, affordability, digital skills, and the ability to use online services effectively.
A high-speed connection may be technically available in an area but still be difficult for some households to afford.
Rural and remote communities can also face infrastructure challenges that are less common in densely populated areas.
Internet access therefore involves more than simply whether a cable or cellular signal reaches a particular location.
How has the internet changed communication?
The internet dramatically reduced the practical barriers to communicating across distance.
Email made written communication nearly instantaneous. Messaging platforms allow people to exchange text, images, audio, and video in real time. Social networks allow information to spread rapidly among large audiences. Video conferencing allows people in different locations to communicate face to face.
Communication is no longer limited primarily by physical distance or traditional broadcast infrastructure.
But the same characteristics that make information spread quickly can also allow misinformation, scams, harassment, and other harmful content to spread rapidly.
What are the biggest security threats on the internet?
Internet-connected systems face many different kinds of security threats.
Malware is malicious software designed to damage systems, steal information, disrupt operations, or perform other unwanted actions.
Phishing attempts to trick people into revealing sensitive information, often by impersonating a legitimate organization.
Ransomware can encrypt or otherwise restrict access to data and demand payment from victims.
Credential attacks attempt to obtain or exploit usernames and passwords.
There are also vulnerabilities in software, insecure configurations, supply-chain attacks, denial-of-service attacks, and many other threats.
Good cybersecurity therefore depends on multiple layers of protection rather than a single tool.
Why are strong passwords important?
Passwords are often the first line of defense for online accounts.
Weak or reused passwords can allow attackers who obtain one credential to gain access to multiple services.
Using unique, strong credentials for important accounts reduces this risk.
Password managers can help users generate and store unique passwords, while multifactor authentication adds another layer of protection by requiring an additional form of verification.
What is multifactor authentication?
Multifactor authentication, or MFA, requires more than one type of evidence when verifying a user’s identity.
The factors can include something you know, such as a password; something you have, such as a security key or authentication device; or something you are, such as a biometric characteristic.
MFA can make account compromise substantially more difficult because obtaining a password alone may not be enough to gain access.
Can the internet be private?
Internet privacy is complicated.
Information can be exposed at different points depending on the application, network, service provider, device, and security technology being used.
HTTPS can protect the contents of communication between a browser and website, but it does not make a user completely anonymous.
Websites can collect information about visitors. Applications can request permissions. Advertising systems can use tracking technologies. Online services can maintain account records and activity logs.
Privacy therefore depends on both technical protections and the policies and practices of the services people use.
What happens to the internet when you turn off your device?
Your device disconnects from the networks it was using, but the internet itself continues operating.
Other devices, servers, routers, data centers, and network links remain connected.
This illustrates another important characteristic of the internet: it is not a single machine that turns on or off. It is a constantly operating collection of independently managed networks.
Where is the internet physically located?
There is no single physical location called “the internet.”
Its infrastructure is spread across the planet.
It includes:
- Fiber-optic cables
- Submarine cables
- Routers and switches
- Cellular towers
- Wi-Fi equipment
- Data centers
- Computers and smartphones
- Satellites
- Internet exchange points
- Network operations facilities
- Power and cooling infrastructure
The websites and applications people use may feel virtual, but the internet ultimately depends on enormous amounts of physical equipment.
How much energy does the internet use?
The internet requires energy at many stages.
Data centers consume electricity to operate servers, networking equipment, storage systems, cooling systems, and other infrastructure.
Telecommunications networks also require power to operate routers, switches, cellular equipment, cable systems, and other facilities.
Users’ devices consume energy as well.
The energy required for a particular online activity varies enormously depending on the application, hardware, network, data volume, and infrastructure involved.
As internet use and computing workloads grow, improving energy efficiency and using different sources of electricity have become important engineering and environmental considerations.
Why does the internet keep evolving?
The internet was not designed once and then frozen.
New protocols, hardware, wireless technologies, security systems, applications, and network architectures continue to change how it operates.
IPv6 is expanding the available address space. Faster fiber and wireless networks increase capacity. Cloud computing distributes computing resources across enormous infrastructures. Edge computing can move processing closer to users and devices.
At the same time, engineers continue working on security, reliability, privacy, scalability, and ways to support increasingly demanding applications.
The internet’s most fundamental idea remains remarkably simple: independent networks can communicate using shared protocols. Everything from a short message on a phone to a video streamed across an ocean depends on that principle.
