What are the MVC components in the context of web development?

I'm trying to understanding what MVC is, why it's useful, and if I should use it or not.

In the context of dynamic websites, what are the models, views, and controllers? I've seen these as examples before, are they all right or is only one of them right?

• Model: HTML, view: CSS, controller: Javascript


• Model: database, backend processing; view: HTML, CSS, Javascript; controller: HTTP (GET/POST), URLs


• Model: database; view: HTML, CSS, Javascript; controller: backend processing

Are there other examples of MVC in web development?