Packages 
Package Description
javax.el  
javax.servlet
The javax.servlet package contains a number of classes and interfaces that describe and define the contracts between a servlet class and the runtime environment provided for an instance of such a class by a conforming servlet container.
javax.servlet.annotation  
javax.servlet.descriptor  
javax.servlet.http
The javax.servlet.http package contains a number of classes and interfaces that describe and define the contracts between a servlet class running under the HTTP protocol and the runtime environment provided for an instance of such a class by a conforming servlet container.
javax.servlet.jsp
Classes and interfaces for the Core JSP 2.0 API.
javax.servlet.jsp.el
Classes and interfaces for the JSP 2.0 Expression Language API.
javax.servlet.jsp.tagext
Classes and interfaces for the definition of JavaServer Pages Tag Libraries.
javax.websocket  
javax.websocket.server