What are common pitfalls when working with PHP forms, especially when trying to pass and assign values?

One common pitfall when working with PHP forms is not properly assigning values to variables after form submission. To solve this, ensure that form fields are named correctly and use the $_POST superglobal to retrieve values from the form.

// Example of assigning form values to variables
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $username = $_POST["username"];
    $password = $_POST["password"];
    
    // Use the variables for further processing
}