about java servlet concept

Servlet:-
    A servlet is a componet or java class which is run over the servlet container. Servlet completly handle client request and response through HTTP. So that servlet engine must be support HTTP.

For writing a servlet, in java there ia a package javax.servlet.
Javax.servlet Package:-
    javax.servlet package has 7 interfaces, 3 classes and 2 exceptions

Interfaces inside javax.servlet:-
    1)Request Dispatcher
    2)Servlet
    3)Servlet Config
    4)Servlet Context
    5)ServletRequester
    6)ServletResponse
    7)SingleThreadModel
Classes inside javax.servlet:-
    1)GenericServlet
    2)ServletInputStream
    3)ServletOutputStream
Exceptions inside javax.servlet:-
    1)ServletException
    2)UnavailableException