What role does the isset() function play in handling URL parameters in PHP scripts?

The isset() function in PHP is used to determine if a variable is set and is not NULL. When handling URL parameters in PHP scripts, isset() can be used to check if a specific parameter has been passed in the URL. This helps prevent errors when trying to access non-existent parameters in the URL.

// Check if a specific parameter 'id' is set in the URL
if(isset($_GET['id'])){
    $id = $_GET['id'];
    // Use the parameter 'id' in your script
    echo "ID parameter is set to: $id";
} else {
    echo "ID parameter is not set in the URL";
}