One of the really nice things about PHP.net in particular is that you can go to any function name as a root directory on the website and it will look it up, e.g

One of the really nice things about PHP.net in particular is that you can go to any function name as a root directory on the website and it will look it up, e.g. http://php.net/explode http://php.net/explode will go right to the explode doc. This works for root functions as well as classes and most keywords.