What Do Internet Providers Do?
When you open a browser and visit a website, your request travels through cables, routers, and data centers spanning continents. But who builds and maintains all that infrastructure? That's the job of Internet Service Providers (ISPs).
Think of ISPs as highway authorities for digital traffic. They build the roads, maintain them, manage traffic flow, and connect different road systems together. Without ISPs, your devices would have nowhere to send their data.
What ISPs Actually Provide
Physical infrastructure. ISPs own or lease the cables, fiber optic lines, cell towers, and equipment that carry internet traffic. This includes everything from the wire running to your home to undersea cables crossing oceans.
IP addresses. When you connect to the internet, your ISP assigns your network a public IP address. This address identifies you on the global internet.
Routing. ISPs operate routers that direct traffic between networks. When you request a webpage, your ISP's routers figure out the best path to reach the destination server.
DNS services. Most ISPs run DNS servers that translate domain names into IP addresses for their customers.
The ISP Hierarchy
Not all ISPs are equal. The internet has a tiered structure:
Tier 1 ISPs are the giants. They own massive global networks and connect directly to each other without paying for transit. Companies like AT&T, NTT, and Lumen operate at this level.
Tier 2 ISPs have regional networks. They pay Tier 1 providers for global connectivity while also connecting directly to some peers.
Tier 3 ISPs are local providers — the company you pay for home internet. They purchase connectivity from larger ISPs and deliver it to end users.
Peering and Transit
ISPs connect to each other through arrangements called peering (exchanging traffic for free between similar-sized networks) and transit (paying a larger network to carry your traffic globally). These relationships determine how efficiently data flows across the internet.
Why This Matters
Understanding ISPs helps explain why internet speeds vary by location, why some regions have better connectivity, and why major ISP outages can knock large portions of the internet offline. Your connection quality depends heavily on your ISP's infrastructure and their relationships with other networks.