How does the use of isset() compare to if(empty()) in PHP form processing?

When processing form data in PHP, using isset() checks if a variable is set and not null, while empty() checks if a variable is empty or not. It is recommended to use isset() to check if a form field has been submitted, and then use empty() to further validate the input if needed.

// Using isset() to check if form field is set and not null
if(isset($_POST['submit'])){
    // Further validation using empty()
    if(!empty($_POST['name'])){
        $name = $_POST['name'];
        // Process form data
    } else {
        echo "Name field is empty.";
    }
}