PHP: if... else...

<?php
if($age < 18){
echo 'Child'; // Display Child if age is less than 18
} else{
echo 'Adult'; // Display Adult if age is greater than or equal to 18
}
?>

OR

<?php echo ($age < 18) ? 'Child' : 'Adult'; ?>

Create Contact Forms

Populate SELECT dropdown from MySQL database

Send an email with Attachment

Sample Codes (Working)
https://www.codexworld.com/send-email-with-attachment-php/

check required fields using array"
https://www.tutdepot.com/server-side-form-field-validation-with-php-only/

PHP Notes