How Does the Internet Work? From Click to Server in Milliseconds

The Internet Is Not the Cloud — It's Cables

Despite the ethereal language we use — 'the cloud,' 'wireless,' 'streaming' — the internet is overwhelmingly physical. About 95% of intercontinental internet traffic travels through undersea fiber optic cables lying on the ocean floor. As of 2024, there are approximately 550 active submarine cables spanning over 1.4 million kilometers — enough to wrap around Earth 35 times.

These cables are roughly the diameter of a garden hose but carry virtually all of the world's digital communication: emails, video calls, financial transactions, streaming video, and the webpage you're reading right now. A single modern cable like Google's Grace Hopper (connecting the US, UK, and Spain) can transmit 340 terabits per second — enough to transfer the entire Library of Congress in a fraction of a second.

The cables are vulnerable. They're laid by specialized ships that unspool cable from massive drums, lowering it to the ocean floor at depths of up to 8,000 meters. Shark bites, ship anchors, earthquakes, and even sabotage have damaged cables. In January 2022, the Tonga volcanic eruption severed the island nation's only submarine cable, cutting off 100,000 people from the internet for five weeks.

On land, data travels through a hierarchy of networks: backbone networks (massive fiber lines operated by companies like Lumen, Telia, and NTT), regional networks, and 'last mile' connections to your home via fiber, cable, or copper telephone lines. 'Wi-Fi' is only the final 30 meters — from your router to your device.

What Happens When You Type a URL

When you type 'google.com' into your browser, a precise sequence of events unfolds in roughly 100-300 milliseconds.

Step 1: DNS Resolution. Your browser needs to convert 'google.com' into a numerical IP address (like 142.250.80.46). It first checks its local cache. If it doesn't have the answer, it asks your router, then your ISP's DNS server. If nobody knows, the query escalates to one of 13 root DNS server clusters that anchor the entire internet's naming system. The root server directs the query to the .com servers, which direct it to Google's authoritative DNS server, which returns the IP address. This entire chain typically completes in 20-50 milliseconds.

Step 2: TCP Connection. Your computer initiates a TCP (Transmission Control Protocol) connection to Google's server using a 'three-way handshake': your machine sends a SYN (synchronize) packet, the server responds with SYN-ACK (synchronize-acknowledge), and your machine confirms with ACK. This takes one round-trip time — about 10-30ms to a nearby server.

Step 3: TLS Encryption. For HTTPS sites (virtually all modern websites), a TLS handshake establishes encrypted communication. Your browser and the server agree on encryption methods and exchange cryptographic keys. This adds another 1-2 round trips.

Step 4: HTTP Request. Your browser sends an HTTP GET request asking for the webpage. The server processes the request and sends back HTML, CSS, JavaScript, images, and other resources — often in compressed form to reduce transfer time.

Step 5: Rendering. Your browser parses the HTML, applies CSS styles, executes JavaScript, and paints the pixels on your screen. Modern browsers can display the first meaningful content within 200-500ms of the initial click.

Data Packets: How Information Actually Travels

The internet doesn't send files as complete units. Every piece of data — whether it's an email, a video frame, or this sentence — is broken into small chunks called packets, typically around 1,500 bytes each (about 1,500 characters of text).

Each packet contains a header with routing information: the source IP address, destination IP address, sequence number (so packets can be reassembled in order), error-checking data, and the protocol being used. Think of it like putting a letter in an envelope with the sender and recipient addresses written on it.

Packets from the same file can take completely different routes through the network. A video stream from Netflix might have some packets routed through Chicago and others through Dallas, depending on real-time network conditions. Routers along the way examine each packet's destination and forward it toward the next hop, making routing decisions in nanoseconds using enormous routing tables.

TCP (Transmission Control Protocol) ensures reliability. If a packet is lost or corrupted during transit — which happens regularly due to network congestion, hardware errors, or interference — TCP detects the gap and requests retransmission. It also handles flow control, slowing down transmission if the receiving end can't keep up.

UDP (User Datagram Protocol) is TCP's faster but less reliable cousin. It skips error-checking and retransmission, which makes it ideal for real-time applications where speed matters more than perfection: video calls, online gaming, and live streaming. A dropped frame in a Zoom call is better than a delayed one.

At peak usage, the global internet carries approximately 1 exabyte (one billion gigabytes) of data per day. To put that in perspective, if each gigabyte were a brick, you could build 200 Great Walls of China every single day.

IP Addresses, DNS, and the Internet's Phone Book

Every device connected to the internet has a unique IP (Internet Protocol) address. IPv4 addresses look like 192.168.1.1 — four numbers from 0 to 255. This system provides about 4.3 billion unique addresses, which seemed limitless when designed in 1981 but has been exhausted since 2011.

IPv6 was created to solve this, using 128-bit addresses written in hexadecimal (like 2001:0db8:85a3:0000:0000:8a2e:0370:7334). IPv6 provides 340 undecillion addresses — roughly 340 followed by 36 zeros. That's enough to assign a unique address to every atom on Earth's surface.

The Domain Name System (DNS) is often called 'the phone book of the internet.' Humans remember names (google.com); computers need numbers (142.250.80.46). DNS translates between the two. The system is hierarchical: 13 root server clusters (named A through M, operated by organizations like NASA, the US Army, and ICANN) sit at the top, directing queries downward to top-level domain servers (.com, .org, .uk) and then to authoritative servers for individual domains.

DNS was designed by Paul Mockapetris in 1983 and remains one of the most critical pieces of internet infrastructure. A DNS failure can effectively make websites 'disappear' even though their servers are running fine. In October 2021, a Facebook configuration error removed their DNS records from the internet, making Facebook, Instagram, and WhatsApp unreachable for approximately 3.5 billion users for six hours. The company estimated the outage cost them over $100 million in lost advertising revenue.

Who Runs the Internet? Nobody (and Everybody)

One of the most remarkable things about the internet is that no single entity owns or controls it. It's a network of networks — thousands of independent networks voluntarily interconnecting under shared protocols.

Several organizations coordinate different aspects. ICANN (Internet Corporation for Assigned Names and Numbers) manages the domain name system and IP address allocation. The IETF (Internet Engineering Task Force) develops and maintains the technical standards (called RFCs — Requests for Comments) that govern how internet protocols work. The World Wide Web Consortium (W3C) standardizes web technologies like HTML, CSS, and JavaScript. Regional Internet Registries allocate IP addresses to ISPs in their geographic areas.

Internet Service Providers (ISPs) operate at different tiers. Tier 1 ISPs (like Lumen Technologies, Telia Carrier, and NTT Communications) own global backbone networks and peer with each other freely — they don't pay anyone for transit. Tier 2 ISPs purchase some transit and peer with others. Tier 3 ISPs (your local broadband provider) buy transit from higher-tier networks and sell access to end users.

Internet Exchange Points (IXPs) are physical locations where networks meet to exchange traffic directly, rather than routing through third parties. Major IXPs like DE-CIX in Frankfurt handle peak traffic exceeding 17 terabits per second. Direct peering reduces latency and costs.

Content Delivery Networks (CDNs) like Cloudflare, Akamai, and AWS CloudFront cache copies of popular content at servers worldwide. When you load a YouTube video, you're likely watching it from a server in your own city, not from Google's headquarters in California. CDNs serve an estimated 50-70% of all internet traffic.

Sources: TeleGeography Submarine Cable Map (2024), Cisco Annual Internet Report, Facebook Incident Report (October 2021), ICANN, DE-CIX traffic statistics.