What types of HTTP requests are there?

Main types of HTTP requests: GET, POST, PUT, DELETE, PATCH, HEAD, OPTIONS, TRACE, CONNECT.

Description of the most common:

• GET: Requests a representation of the specified resource. Requests using this method should only retrieve data.
• POST: Sends data to be processed to a specific resource. A common result is a change in state or side effects on the server.
• PUT: Replaces all current representations of the target resource with the data from the request body.
• DELETE: Deletes the specified resource.
• PATCH: Applies partial modifications to a resource.
• HEAD: Requests headers similar to GET, but without the response body. Used for obtaining metadata.
• OPTIONS: Describes communication parameters for the target resource.
• CONNECT: Converts the request to a transparent TCP/IP proxy connection.
• TRACE: Performs a message loop-back test along the path to the target resource.

Differences between GET and POST:

Attribute	GET	POST
Purpose	Retrieve data	Send data for processing
Data transmission	Via URL parameters (Query String)	Via request body
Security	Idempotent (repeated requests do not change state)	Not idempotent
Data visibility	Visible in URL, stored in browser history, server logs	Not visible in URL, not stored in browser history
Data size	Limited by URL length	Unlimited (or very large)
Caching	Can be cached	Not cached by default
Bookmarks	Can add a page with GET parameters to bookmarks	Cannot (for regular form submission methods)

Example of using GET in PHP:

<?php
// Getting the 'id' parameter from URL
$userId = $_GET['id'];
echo "User ID: " . htmlspecialchars($userId);
?>

Example of using POST in PHP (form data processing):

<?php
// Check if the request method is POST
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    // Get data from request body
    $username = $_POST['username'];
    $password = $_POST['password'];
    // Further processing of data (e.g., saving to database)
    echo "Username: " . htmlspecialchars($username) . "<br>";
    echo "Password received.";
}
?>