 <p>Yes, that is a much more complicated task. You're going to have to store the last modified time into a database (since you're saying users can modify their profile content I'll assume you already have a database). The easiest way to get the last time the user modified their profile depends on your schema.</p> <p>To put it another way... what the user is actually modifying isn't "profile.php", it's some data that lives elsewhere, e.g. a MySQL database; so the system that's going to know when the user last modified it is that external data source.</p>