DLLs & Lib files

Hi,

My apologies, this isn't much of a programming question, although you're the guys who are likely to know. ;)

Please explain the difference between dll's and lib files, and how they fit in with DLL export declerations in a source file. Also, how I can go about viewing the contents of each  - dll's there's a Visual Studio tool I can use to see the function defintions contained?, but I don't know about libs.

Thanks,
Uni