Servlets are server-side Java applications. Most contemporary Web servers and application servers provide support for servlets in some fashion. Many other server-side technologies are based on servlets, e.g. JavaServer Pages (JSP). Note that in recent years interest in Java servlets per se has been overtaken by interest in J2EE application servers.
To be included in this category: Significant Web applications that are packaged as servlets.

General servlet resource belong in Java/Server-Side/Resources/.

Servlet tutorials belong in Java/Server-Side/Tutorials/.

JavaServer Pages submission go in JSP.

Applications implemented as Java Servlets. This category for actual software products you can use that are created using Java servlets. Also included are development toolkits which implement enough functionality that the user of the toolkit does not need to use the servlet API directly.
Submit web toolkits which build servlets and applications implemented as Java servlets to this category. Do not submit servlet resources, or tutorials.
A servlet engine, also known as a container, is essentially a webserver which is capable of executing Java servlets.
Submit only links to web server applications which are servlet enabled. This category should not be used to describe an application which is implemented with Java servlets. It is only for the servlet containers themselves.