I'm in the big confusion . What are these things django, flask,ruby on rails ,servlets, in python and what is the use. I know it's a web application framework but what does it do.many terms like "JSON,XML,"and what is the relationship between those term above with server side and client side application.what if I learn above stuff and what job will I get ? I heard that service side job is more pressured than product based job.and what are the service based and product based jobs ?what are the course that I need to learn to join in product based job. I have no clear vision . Can any one give a clear vision about this