The internet is built on cables, not magic

The internet reaches your home through physical cables buried underground, strung on poles, or run through the ocean floor. These cables carry data as electrical or light signals between buildings, cities, and continents. Your internet service provider (ISP) owns or leases some of these cables and connects them to your house. The cables themselves are owned and maintained by telecommunications companies, some of which are also ISPs, and some of which only rent space to other companies.

When you click a link or send an email, your data travels through multiple cables and switches owned by different organizations. No single company owns the entire internet. Instead, thousands of networks operated by ISPs, tech companies, universities, and governments are connected to each other through agreements that let data pass between them.

Key Takeaways

  • The internet physically exists as cables, fiber optic lines, and radio towers that carry data between your home and distant servers.
  • Your ISP connects you to the broader internet by running a cable to your house and linking it to larger networks they own or lease.
  • Data travels through multiple networks owned by different companies, each agreeing to pass your traffic along to the next network.
  • Undersea cables connect continents and carry the majority of international data, while terrestrial cables handle local and regional traffic.
  • The physical infrastructure is expensive and takes years to build, which is why some areas have only one or two ISP options.

How cables connect your home to the wider internet

Your ISP runs a cable from a nearby hub or central office to your house. This cable is usually coaxial (the kind used for cable TV), fiber optic (thin glass strands that carry light), or copper telephone wire, depending on what infrastructure exists in your area. The cable enters your home, connects to a modem, and the modem converts the signal into data your devices can use.

That cable does not go directly to Google or Facebook. Instead, it connects to your ISP's local network, which is a collection of cables and equipment in your city or region. Your ISP's network then connects to larger networks called backbone networks, which are the main highways of the internet. These backbone networks are operated by companies like Lumen, Verizon, and AT&T, as well as tech companies like Google and Meta that have built their own private networks.

When your data reaches a backbone network, it travels through multiple switches and routers that read the destination address and send it toward the right network. If your data is going to a server in another country, it may travel through an undersea cable. If it is staying local, it might only pass through a few switches before reaching its destination.

Undersea cables carry data between continents

International data travels through cables laid on the ocean floor. These cables are about the thickness of a garden hose and contain fiber optic strands that transmit data as pulses of light. Hundreds of these cables crisscross the world's oceans, connecting every continent except Antarctica.

A single undersea cable can cost hundreds of millions of dollars to lay and takes years to plan and install. Ships specially designed for cable installation lower the cables to the seafloor, and the cables are buried in shallow water to protect them from ship anchors and fishing equipment. Tech companies like Google, Meta, and Amazon have begun funding and building their own undersea cables because the existing cables are congested and expensive to use.

When you stream video from a server in Europe or send a message to someone in Asia, your data likely travels through one of these undersea cables. The journey takes milliseconds, but the physical distance is thousands of miles. If a cable is damaged by a ship anchor or earthquake, data is rerouted through other cables, which is why the internet usually stays up even when individual cables fail.

Your ISP is one piece of a much larger system

Your ISP is responsible for the last mile — the cable from the central office to your house. They are not responsible for the backbone networks or undersea cables that carry your data across the country or world. Instead, your ISP pays other companies for access to those larger networks, or they own pieces of them.

Large ISPs like Comcast, Verizon, and AT&T own significant portions of the backbone and undersea cable infrastructure. Smaller regional ISPs lease access to backbone networks from larger companies. This is why your bill includes charges for internet service — you are paying your ISP for the cable to your house and for their access to the broader internet infrastructure.

The agreements between networks are called peering agreements. When two networks peer, they agree to exchange traffic without charging each other. When one network needs to send traffic through another network's infrastructure, they pay for that access. These agreements are negotiated between companies and are not visible to you, but they determine how fast your data travels and which route it takes.

Data centers and servers are the destinations

The cables and networks are the roads. The data centers are the buildings where the actual servers live. A data center is a large facility filled with thousands of computers stacked in rows, all connected to power supplies, cooling systems, and high-speed internet connections. Google, Amazon, Microsoft, Meta, and other tech companies operate data centers around the world.

When you visit a website or use an app, your request travels through the cables and networks until it reaches a data center where the website or app's servers are located. The server processes your request, sends the data back through the same cables and networks, and your device displays the result. This entire journey usually takes less than a second.

Data centers are connected to the internet backbone with multiple high-speed cables so that data can move in and out quickly. A single data center might have thousands of servers, and a company like Google operates dozens of data centers across the globe. This is why you can load a website quickly even if the server is thousands of miles away — the cables and networks are built to move data at the speed of light.

Why some areas have limited ISP choices

Building the physical infrastructure to deliver internet to a home is expensive. A company has to dig trenches, lay cables, install equipment, and maintain it all. Because of this cost, many areas have only one or two ISPs. In cities, multiple companies may have already laid cables, so you might have three or four choices. In rural areas, the cost per customer is much higher, so companies are less likely to build there.

Some communities have built their own municipal broadband networks to provide internet where private ISPs would not. These are usually operated by the city or county and use the same cable infrastructure as private ISPs. A few states have laws that make it hard for municipalities to build their own networks, which limits choices even further in those areas.

The Federal Communications Commission (FCC) tracks broadband availability and has programs to fund infrastructure in underserved areas. However, building new infrastructure takes years, so if you live in an area with limited choices today, that situation may not change soon.

Wireless internet is also physical infrastructure

Not all internet connections use cables. Wireless internet from cell towers, satellite, and fixed wireless providers also relies on physical infrastructure. Cell towers are connected to the internet backbone through fiber optic cables, and they transmit data to your phone or wireless router using radio waves. Satellite internet uses dishes on the ground and satellites in orbit, with cables connecting ground stations to the internet backbone.

Wireless connections are often slower and less reliable than wired connections because radio waves are affected by weather, distance, and obstacles. However, wireless is the only option in some areas where laying cables is not practical. As technology improves, wireless speeds are increasing, and more people are using it as their primary internet connection.

Frequently Asked Questions

Who actually owns the internet?

No single person or company owns the internet. Thousands of networks owned by ISPs, tech companies, governments, and universities are connected to each other. Each organization owns and operates their own network, and they agree to exchange traffic through peering agreements. The infrastructure is distributed across many owners, which is why the internet continues to work even if one company's network fails.

How fast does data travel through cables?

Data travels through fiber optic cables at nearly the speed of light, which is about 186,000 miles per second. In practice, data takes a few milliseconds to travel across the country because it has to pass through multiple switches and routers that read the destination address and decide where to send it next. The actual speed of light in fiber is slightly slower than in a vacuum, and the equipment adds small delays.

What happens if an undersea cable breaks?

If an undersea cable breaks, data is automatically rerouted through other cables. Most international routes have multiple cables, so losing one does not cut off communication. However, if a heavily used cable breaks and there are not enough other cables to handle the traffic, internet speeds in that region may slow down temporarily. Repair ships are dispatched to fix the cable, which usually takes a few weeks.

Can I see the cables that carry my internet?

You can see some of them. Cables on telephone poles are visible along streets. Cables buried underground are not visible, but you might see the metal boxes where cables enter buildings. Undersea cables are not visible unless you are diving on the ocean floor. Most of the internet infrastructure is hidden because it is buried, underwater, or inside buildings.

Why do I need a modem if I already have internet?

Your ISP's cable carries data in a format that your devices cannot understand directly. A modem converts that signal into data your computer, phone, or router can use. Without a modem, the cable is just a physical connection with no way to translate the signal. Your router then takes that data and broadcasts it wirelessly to your devices or connects them through ethernet cables.