$_SESSION
` superglobal array. This array contains all the session variables and their values.<?php
// Start the session
session_start();
// Set a session variable
$_SESSION['username'] = 'john';
// Get the session variable value
$username = $_SESSION['username'];
// Print the variable value
echo "Username: $username";
?>
Username: john
session_start()
` function. We then set a session variable named `username` to the value `'john'`. Finally, we retrieve the value of the `username` variable from the `$_SESSION
` array and print it to the screen using `echo
`.session_start()
` at the beginning of your program, before any output is sent to the browser. Also, you should avoid using sensitive information as session variable names or values.