Where we will use Servlet and JSP in J2EE projects?
For what purpose we are using that?

jese is a stand alone application where as j2ee is web based application
we can have client server intereaction jsp is mostly for front poage design and client side validation but servlet is for serverside validation

In J2ee,
In general, Servlet and jsp is used for web based apllications in server side programming purpose.
Jsp is using as Large View purpose.mainly to develope the Presentaions or frond apllication purpose.

Servlet is also doing same thing , and in case of Struts Framework, Servlet acts as controller between the request comming from the browser and Server.

J2ee is used for web application development, it follows MVC architecture.
Jsp is used a View
Servlets are used for Controller.

After struts framework has introduced, most the companies are using Struts frameworks only, advantages of using struts is, it has built in Controller, so need write any controller functionality need to write Action classes and Form beans