Newb question: instances of classes vs models?

[eluser]toopay[/eluser]
M stand for Model : class for handle all of your database abstraction
V stand for View : a file which you used for outputing your http response. Ussually just a html structure file with pseudo variable mark-up
C stand for Controller : class for handle all of your logic, which decide the output/result for every HTTP request

Library, is just a class contain reusable or usefull function, which you may need in most of your controller, model, or even in your view.