what is filter_validate_email in php code example

Example: php filter validate email

<?php
$email_a = '[email protected]';
$email_b = 'bogus';

if (filter_var($email_a, FILTER_VALIDATE_EMAIL)) {
    echo "L'adresse email '$email_a' est considérée comme valide.";
}
if (filter_var($email_b, FILTER_VALIDATE_EMAIL)) {
    echo "L'adresse email '$email_b' est considérée comme valide.";
} else {
    echo "L'adresse email '$email_b' est considérée comme invalide.";
}
?>