How Networking & Internet Works

The internet is a global network of billions of devices — computers, phones, servers — all connected and able to talk to each other. When you load a webpage, your device sends a request across this network, the right server receives it, and the response travels back to your screen in under a second. Understanding how that happens reveals one of the most impressive engineering achievements in human history.

DNS — the Domain Name System — is the internet's phone book. Every website has a numeric IP address like 104.21.33.72, but humans use names like "google.com". DNS is the system that translates one into the other. Every time you visit a website, a DNS lookup happens in the background — usually in under 50 milliseconds — before your browser can even start loading the page.

A VPN (Virtual Private Network) creates an encrypted tunnel between your device and a VPN server. All your internet traffic is routed through this server — websites see the VPN server's IP address instead of yours, and your ISP sees only encrypted traffic to the VPN server rather than the sites you visit. This provides privacy from your ISP, IP address masking from websites, and security on public WiFi.

A search engine has three core systems: a crawler that continuously visits billions of web pages; an indexer that organises what it finds into a giant lookup table; and a ranking algorithm that, given a search query, retrieves and orders the most relevant results in milliseconds. Google's crawler visits billions of pages daily, its index stores hundreds of billions of documents, and its ranking system considers over 200 signals to return results within 200 milliseconds of your search.

HTTPS is HTTP with an encryption layer called TLS (Transport Layer Security). Before any data is exchanged, your browser and the server perform a handshake — agreeing on encryption methods, verifying the server's identity via a digital certificate, and exchanging keys. All subsequent communication is encrypted so that no one intercepting the traffic can read it. The padlock icon in your browser means this handshake succeeded.

Cloud computing delivers computing resources — servers, storage, databases, networking, software — over the internet on demand, billed by usage rather than owned outright. Virtualisation technology allows one physical server to run dozens of independent virtual machines simultaneously. Providers like AWS, Azure, and GCP operate millions of servers in data centres worldwide, and you rent fractions of them instantly through APIs. Cloud computing enables businesses to scale from zero to global in minutes without buying hardware.