Servlets running together in the same server communicate with each other in several ways. The three major reasons to use interservlet communication are:

a) Direct servlet manipulation - allows gaining access to the other currently loaded servlets and performing certain tasks (through the ServletContext object)

b) Servlet reuse - allows the servlet to reuse the public methods of another servlet.

c) Servlet collaboration - requires to communicate with each other by sharing specific information (through method invocation)