HTML container tags - proper usage

Question

I've been building websites for a while, but I've never really encountered a discussion about how the container tags should be used. In the collection tags, I've seen a wide range of content types, but it generally seems that the page's author simply chooses a style they prefer and sticks with it.

In my perspective, the biggest difference is between

<p> 

<div>

but I'd also like your thoughts on

<span> 

as well as any others I might have forgotten.