Servlet, JSP..

What is the difference between JSP and Servlet?

How can JSP and Servlet communicate with each other?

How to track an user? (Session and cookies)

How to create a session in servlets?

How will you implement a page counter using Jsp/Servlet? Where will you initialize the variable and where will it get incremented? What will happen to it, when the server crashes?

Do you have used any Servlet filters? What is a filter?

Can a servlet have a constructor? (No.)