[vehemenz]

I am a fan of PHP's official documentation. It's well organized, terse, and relies heavily on exemplification.

As a bonus, you get more examples in the comments—kind of like Stack Overflow, but attached to a particular feature or process of PHP.

[acherion]

The PHP documentation is excellent. I wish other PHP projects / frameworks like Laravel had clear, concise, down to earth documentation like PHP.net's, and doesn't require me to have a degree in computer science to understand the terminology.