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What are HTTP requests?

HTTP requests are messages sent by the client to initiate an action on the server.

Start-line

The start-line of HTTP requests contains three elements:

1. HTTP method

HTTP verbs indicate the action to be performed. These actions include:

  • GET: fetch a resource
  • POST: push data to the server to create a new resource
  • DELETE: delete a resource from the server
  • PUT: update a resource on the server

2. Request target

Target is usually a URL. Options include:

  • Absolute path followed by a ? and query string.
    • This is the most common form and is used with HTTP methods.
  • Complete URL (absolute form)
    • Mostly used with GET when connected to a proxy.
  • Authority component of URL
    • Consists of the domain name and the port (optional).
  • Asterisk form
    • A simple asterisk (*) used with OPTIONS, representing the server as a whole.

3. HTTP version

Defines the structure of the remaining message, acting as an indicator of the expected version to use for the response.

Headers

HTTP request headers

Source: MDN Web Docs

HTTP headers let the client and the server pass additional information with an HTTP request or response.

A request header is a type of HTTP header that can be used in a request to provide information about the request context, so that the server can tailor the response.

Headers are in key-value pairs separated by a colon.

A representation header is a type of HTTP header that describes the particular representation of the resource sent in an HTTP message body.

Example:

Content-Length: 100

Body

The body is the final part of an HTTP request. Not all requests need one, such as GET, HEAD, DELETE, or OPTIONS.

Sources