How the internet works, in one sitting

The internet is a network of networks. No single company owns it, and no single computer controls it. It works because millions of devices agree on common protocols for moving data.

Here is the short version of what happens when you open a website.

1. Your device joins a network

Your phone or laptop connects to a router, usually over Wi-Fi. The router connects to your internet provider, which connects to larger networks. Your device gets an IP address, a numeric label used to route traffic.

2. The name is translated

You type simplytools.us. Computers use IP addresses, not names, so your device asks a DNS (Domain Name System) resolver to translate the domain into an address. DNS is a distributed directory; answers are cached at many levels to keep lookups fast.

3. A connection is opened

Your browser opens a connection to the server using TCP (or a newer protocol such as QUIC). The data is broken into packets, numbered, and anything that goes missing is retransmitted. TCP provides the reliable connection; the Internet Protocol (IP) below it handles addressing and routing each packet.

For HTTPS, the browser and server then perform a TLS handshake. They agree on encryption keys and verify the server's certificate. After that, the contents of the connection are encrypted, so your ISP or a public Wi-Fi operator cannot read the page contents in transit.

4. The request travels

Your browser sends an HTTP request: a method such as GET, a path, headers and sometimes a body. The request is split into packets. Each packet is routed independently across networks, hopping from router to router, often taking different paths.

Packets can arrive out of order. TCP reassembles them at the destination.

5. The server responds

The server might be a single machine or a fleet behind a load balancer. It may use a CDN (content delivery network) to serve static files from a location near you. It sends back a status code, headers and the content — HTML, images, scripts, fonts and data.

6. The browser builds the page

The browser parses the HTML into a document, downloads CSS and JavaScript, and renders the result. JavaScript can fetch more data and change the page after it loads. This is why a page can appear quickly and then fill in.

7. Caches everywhere

Your browser, your router, your ISP, DNS resolvers and CDNs all keep copies of data. Caching makes the web fast, but it also explains why you sometimes see an old version of a page.

The layers, briefly

Each layer hides complexity from the one above it. That separation is a big part of why the internet has scaled for decades.

The next time a page feels slow, the delay could be in Wi-Fi, DNS, the route, the server, the CDN or the browser. "The internet is down" is usually much more specific than that.