What is the best programming language for web development?
If there was one “best” programming language, then everything else would be obsolete. The reality is that there are so many different programming languages because there is no “best” language for any situation.
Web development can vary from a few hundred to millions of dollars depending on what is needed. You may simply need some changes to something that already exists, or you'd like to build a large or complex application.
As web development evolved, it separated into logical specialization: front end web development and back end development. While back end development involves the server-side development, front end is the final rendering.
Full stack web development as a term evolved due to the separation of roles between front end and back end developers. A “full stack” developer is a developer that can work in both front end and back end technologies.