Tips for golfing in PHP
Understand how variables and whitespace interact with PHP's language constructs.

In my (admittedly short) time golfing, I have found that PHP's language constructs (e.g. echo, return, for, while, etc) behave in a less-than-intuitive way when interacting with variables and whitespace.

echo$v;, for example, is perfectly valid, as are return$v; and other similar constructs. These small reductions in whitespace can lead to a significant cumulative decrease in length.

Keep in mind, though, that variables before language constructs require a space after, as in the following example:

foreach($a AS$b){}


Because AS is a language construct, a space is not required before the variable $b, but if one were to omit the space before it, resulting in $aAS, this would be parsed as a variable name and lead to a syntax error.