A servlet engine handles requests for servlets, JSP files, and other types of server-side include coding. The servlet engine creates servlet instances, loads and unloads servlets, creates and manages request and response objects, and performs other tasks for managing servlets effectively.
In the WebSphere administrative domain, each application server contains zero or one servlet engines. The Web server plug-ins provided by the WebSphere Application Server product help supported Web servers pass servlet requests to servlet engines.