What is the proper way to write the following code?

Hey guys!

I have seen on the internet a couple of ways to write the following statement but the latter one looks a bit weird with that extra opening ( before !isset, which way is the norm here?

if (isset($_POST[‘room’]) || ($_POST[‘cottage’]) || ($_POST[‘villa’])) {

but I have seen somewhere that you can also write if ((!isset($_POST[‘submit’])) || ($_GET[‘u_uid’]))

Which language is this? Looks PHP-ish. Also, what exactly is the code supposed to do?