I don't know C, but need to interact with some C files in a project. I'm noticing that some files have `.lib` extension, while others (which are also supposed to be libraries) have `.c` and `.h` files only in a big folder. 

* What's the difference between these libraries.
* Are the `.c` and `.h` folders also libraries.
* Is the `.lib` format the official format for libraries and these guys who did `.c` and `.h` just lazy or not using best practice?