I want to expand my knowledge of PHP, not necessarily to actually write it myself, but to understand better what it can do and how it can be integrated into websites so I can do a better job of understanding what's possible, conceiving websites, communicating with people, web development etc.

Had a look around the web but all the forums and websites I'm finding don't really have much in the way of "idiot's guide" introductions, they just talk about different functions and so on you can do which make very little sense to me without knowing some of the core essentials, once I have that I'm happy to continue any learning by following forums/blogs etc.

Any recommendations from other users on good starting points? Ideally websites but books are great too.