A request is a compact set of directions
A phone does not send a server a vague plea for “the page.” Its app uses HTTP, the web’s request-and-response protocol, to specify an action—such as fetching a file—and identify the resource it needs. The request can also include headers: small pieces of information about the app, the response format it can handle, or whether it already has a cached copy.
“Text-based” describes the readable structure of traditional HTTP messages, not necessarily every bit sent over today’s networks. Newer versions package the same kinds of instructions differently, but the server still receives a request it can interpret and act on.
From the phone to the right server
Before the request can be answered, the phone needs to reach the right machine. A domain name such as a website address is looked up to find a network address; the connection is then established, with HTTPS adding an encrypted layer. Encryption turns the request and response into data that outsiders on the route should not be able to read or alter, even though the network still needs enough routing information to deliver them.
The server processes the request and returns a response: data, a status indicating what happened, and details about how the phone should handle the result. A page may require many requests—for its text, images, and other files—so loading a screen is often a sequence of small exchanges rather than one download. If one needed file is slow or unavailable, the rest of the page may arrive while that piece is still missing.
