When you click a link, your request leaves your device, races through copper, radio waves, and glass fibers at two-thirds the speed of light, bounces through a dozen routers on three continents, and the answer arrives back on your screen in less time than it takes to blink. The entire round trip: about 60 milliseconds.
The internet is not wireless. It is not "the cloud." It is 1.4 million kilometers of physical cable, most of it sitting on the ocean floor, carrying your data as pulses of light through glass fibers thinner than a human hair.
Most people picture the internet as something that floats in the air, maybe bouncing between satellites or living inside a data center somewhere. The reality is far more physical. About 95% of intercontinental internet traffic travels through roughly 600 submarine fiber optic cables laid across ocean floors. These cables are about the diameter of a garden hose, armored against shark bites and anchors, and they connect continents at speeds nothing else can match. When your video call reaches someone across the Atlantic, the data is not beaming through space. It is racing through a glass thread on the seabed.
The internet's core mechanism is packet switching. When you load a webpage, your computer does not send the request as one continuous stream. It breaks the data into small labeled chunks called packets, each carrying up to 1,460 bytes of payload plus a header that says where it came from, where it is going, and what position it occupies in the sequence. These packets travel independently. They can take completely different physical routes across the globe. At the destination, TCP (Transmission Control Protocol) reassembles them in the correct order.
Before any of that happens, your computer needs to figure out where to send the packets. You typed "google.com," but routers do not understand words. They understand IP addresses: numerical labels like 142.250.80.46. So your browser first queries the DNS (Domain Name System), the internet's phone book. Your device checks its local cache, then asks your ISP's DNS server, which may ask a root server, then a top-level domain server (.com), and finally the authoritative server for google.com. The answer comes back with the IP address, and now your packets have a destination.
Each packet enters the network and hits a router, a device that reads the destination IP and decides which direction to forward it. The router does not know the full path. It only knows which of its neighbors is the best next hop toward that destination, based on its routing table. The packet bounces from router to router, typically passing through 10 to 20 hops before arriving. Each hop adds a small amount of latency: the time to read the header, consult the table, and forward. The biggest contributor to latency is not the routers themselves. It is the physical distance the light must travel between them.
Why does physical distance still matter?
Light in fiber travels at about 200,000 kilometers per second, roughly two-thirds the speed of light in a vacuum. That sounds impossibly fast, but the distances involved are enormous. A round trip from New York to London through submarine cable is about 12,800 kilometers. At fiber speed, the signal propagation alone takes about 64 milliseconds. No software optimization, no faster router, no better protocol can reduce that number. It is limited by the speed of light in glass.
This is why CDNs (content delivery networks) exist. Companies like Cloudflare, Akamai, and AWS place copies of popular content on servers in hundreds of cities worldwide. When you load a webpage, you are probably connecting to a server 50 kilometers away, not 6,000. The data center industry's entire business model is a response to this single physical constraint: light is fast, but the Earth is big.
The thing nobody planned for
The internet was designed to survive a nuclear war. It was not designed for 5 billion people streaming video simultaneously.
The original design of the internet, packet switching with decentralized routing, is what makes it resilient. No single point of failure can take down the whole network because packets simply find another path. But that resilience is only as good as the number of available physical paths. As more of the world's economy depends on the internet, the gap between the network's logical elegance and its physical vulnerability keeps getting more consequential.
The next time you load a webpage and it appears instantly, consider what just happened. Your device translated a name into a number, split your request into labeled packets, sent them racing through copper and glass at two-thirds the speed of light, across a dozen routers, possibly through a cable on the ocean floor, to a server that assembled your request, generated a response, and sent it back the same way. The whole thing took less time than a human reflex. The internet is not magic, and it is not abstract. It is an engineering project of staggering physical scale, doing something that would have seemed impossible a generation ago: making distance almost irrelevant for the movement of information.