What are some potential pitfalls to consider when implementing a voting and notification system using PHP?

One potential pitfall to consider when implementing a voting and notification system using PHP is the risk of vote manipulation through multiple voting by the same user. To prevent this, you can implement a restriction that allows each user to vote only once.

// Check if the user has already voted
if (!isset($_SESSION['voted'])) {
    // Process the vote
    $_SESSION['voted'] = true;
    // Notify the user that their vote has been recorded
    echo "Thank you for voting!";
} else {
    // Notify the user that they have already voted
    echo "You have already voted.";
}