How the Internet Is Built: Cables, ISPs and Data Centers

The internet is a network of networks. Thousands of independently run networks (ISPs, cloud providers, universities and companies) connect through physical cables and agree to exchange traffic using shared protocols. Most of the long-distance links are fibre-optic cables, and submarine cables carry the large majority of intercontinental data. No single organisation owns or runs it.

This guide covers the physical and organisational layers: the cables, the providers, the exchange points, the routing and naming systems, and the data centers. If you want the software side of a single page load, read how the internet works: the request lifecycle first or after.

#Key takeaways

• The internet is physical. Fibre, cables under the sea, routers and buildings full of servers.
• It is a network of networks. Each one is independently operated and connects to others.
• Submarine cables carry over 99% of intercontinental traffic, according to TeleGeography, though it notes the figure rests on dated satellite data.
• Routing is cooperative. Networks announce what they can reach using BGP.
• Naming and addressing are coordinated, but traffic is not centrally controlled.

#The layers, from your device outward

#1. The last mile

Your device connects to your ISP over Wi-Fi, a cable or fibre line, a mobile network or a satellite link. This is the part you pay for and the part that most often limits your speed.

#2. The ISP network

Your ISP aggregates thousands of customers into its own regional network of routers and fibre. It buys or arranges connections to other networks so your traffic can reach the rest of the world.

#3. Backbone and long-haul fibre

Large carriers run high-capacity fibre across countries and continents. Traffic between regions rides these backbones.

#4. Submarine cables

Between continents, data travels in cables laid on the seabed. TeleGeography says the "over 99%" share of intercontinental traffic is accurate, but warns it cannot be calculated precisely without up-to-date satellite figures. Secondary reports of TeleGeography's 2026 map data cite about 694 cable systems including planned ones, with 603 in service. Those counts and cable lengths vary by source, so check TeleGeography's submarine cable map for current figures.

#5. Internet exchange points (IXPs)

An IXP is a facility where many networks plug into a shared switch and swap traffic directly. This keeps local traffic local and cuts cost and latency compared with sending everything through a distant carrier.

#6. Data centers and cloud regions

Websites, apps and databases run on servers in data centers. Cloud providers operate regions made of several facilities connected by their own private fibre. See AWS vs GCP vs Azure.

#7. CDNs

Content delivery networks place copies of content in many locations close to users. That shortens the distance data travels. See CDN explained.

#How networks find each other

Three systems make the whole thing work:

BGP is built on trust between operators. A bad announcement can send traffic the wrong way, which is why route filtering and validation matter and why outages sometimes spread far.

#Who runs the internet?

Nobody runs it as a whole. Different groups own different parts:

• Network operators own and run the cables, routers and data centers.
• Standards bodies such as the IETF write the protocol specifications.
• Address and name coordination is handled by organisations including IANA and ICANN, with regional registries allocating IP addresses.
• Governments regulate providers and landing stations in their own countries.

#What happens when you load a page

In outline: your device asks DNS for an address, sends packets to your ISP, which routes them across networks (possibly through an IXP, a backbone and a submarine cable) to a data center or CDN node. The reply returns by a possibly different path. The delay you feel is mostly distance plus the number of hops. See latency numbers every engineer should know for typical round-trip times.

#Why this matters to builders

• Put servers near users or use a CDN, because distance sets a hard floor on latency.
• Expect failures. Cables get cut and routes flap, so design for retries and redundancy. See reliable AI agents in production for the failure-handling mindset.
• Know your dependencies. Your app depends on DNS, your cloud region and your CDN as well as your own code.

#Need infrastructure that stays fast and up?

We design and deploy web platforms on cloud infrastructure with CDNs, monitoring and failover. Get a scope estimate for your platform.

#FAQ

#How is the internet built?

It is built from fibre-optic cables, submarine cables, routers and data centers owned by many different operators. They connect to each other and exchange traffic using shared protocols.

#Who owns the internet?

No one owns it as a whole. Thousands of networks own their own parts and agree to interconnect. Standards bodies and registries coordinate protocols, names and addresses.

#How much internet traffic goes through undersea cables?

TeleGeography says over 99% of intercontinental data traffic, noting the figure depends on older satellite data and cannot be calculated precisely.

#What is an internet exchange point?

A facility where many networks connect to a shared switch and exchange traffic directly, reducing cost and latency.

#What is BGP?

The Border Gateway Protocol is how networks tell each other which IP addresses they can reach, so routers can pick paths across the internet.

#Is the internet the same as the web?

No. The internet is the network infrastructure. The web is one service that runs on top of it, alongside email, video calls and more.

#Sources

• TeleGeography: Do Submarine Cables Account For Over 99% of Intercontinental Data Traffic?
• TeleGeography Submarine Cable Map