How can PHP be utilized for server-side validation of checkbox inputs in a form?

When dealing with checkbox inputs in a form, server-side validation is crucial to ensure that the correct data is being submitted. To validate checkbox inputs in PHP, you can check if the checkbox is checked or not by using the isset() function. If the checkbox is checked, you can process the data accordingly; if not, you can display an error message.

// Check if the checkbox is checked
if(isset($_POST['checkbox_name'])) {
    // Checkbox is checked, process the data
    $checkbox_value = $_POST['checkbox_name'];
    // Additional validation or processing can be done here
} else {
    // Checkbox is not checked, display an error message
    echo "Please check the checkbox.";
}