Are there any common pitfalls to avoid when trying to keep user selections persistent in PHP applications?

One common pitfall to avoid when trying to keep user selections persistent in PHP applications is not utilizing sessions to store and retrieve the selected values. By using sessions, you can ensure that the user's selections are maintained across different pages or visits to the website.

// Start a session
session_start();

// Set the selected value in a session variable
$_SESSION['selected_value'] = $_POST['selected_value'];

// Retrieve the selected value from the session
$selected_value = $_SESSION['selected_value'];