Brian Moon points out a (sometimes annoying) habit of PHP when it comes to newlines - it drops them after the closing tag.

Have you ever noticed that PHP eats the newlines after a closing PHP tag? Not sure what I mean? There is lots on Google about it. [...] So, why does PHP do this? Well, you have to go back 11 years. PHP 3 was emerging. I was just starting to use it for Phorum at the time. There were two reasons.

The first reason was the it, at least in the minds of the developers of the language, "removed all traces of PHP" from the script without any training newlines to show for it. The second case was a bit more valid - because lots of editors at the time required newlines at the end of every line of code. This caused loads of trouble tracking down things like the infamous "Headers already sent" issues (pre-output buffering).