A servlet is an application or a script that is written in Java and executed on a server, as opposed to on a client. It is analogous to CGI, although servlets are more than simply CGI scripts written in Java.

A Java application that is designed to execute on a webserver instead of on the client's computer. Servlets can be used in the same way that CGI programs...

Extensions that enable all Java servlet metafunctions, including instantiation, initialization, destruction, access from other components, and configuration management. Java servlets are reusable Java applications that run on a web server rather than in a web browser.

Java Servlet technology provides Web developers with a simple, consistent mechanism for extending the functionality of a Web server and for accessing existing business systems.