What potential pitfalls should PHP beginners be aware of when working with form submissions and URL redirection?

One potential pitfall for PHP beginners when working with form submissions and URL redirection is the risk of form resubmission when the user refreshes the page after submitting the form. To prevent this, you can use the Post/Redirect/Get (PRG) pattern, where after processing the form submission, you redirect the user to another page using the HTTP 303 status code to prevent the form from being resubmitted. 

// Check if the form has been submitted
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // Process form submission
    
    // Redirect user to another page to prevent form resubmission
    header("Location: success.php", true, 303);
    exit();
}

Keywords

PHP form submissions URL redirection security vulnerabilities input validation

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