http://www.javaworld.com/javaworld/jw-08-2003/jw-0801-portlet_p.html

Portlets are Java-based Web components, managed by a portlet container, that process requests and generate dynamic content. Portals use portlets as pluggable user interface components that provide a presentation layer to information systems. The next step, after servlets in Web application programming, portlets enable modular and user-centric Web applications. The goal of JSR (Java Specification Request) 168, the Portlet Specification, is to enable interoperability between portlets and portals. This specification defines the contract between portlet and portlet container, and a set of portlet APIs that address personalization, presentation, and security. The specification also defines how to package portlets in portlet applications. Part 1 of this two-part series describes the Portlet Specification and explains its underlying concepts. In Part 2, the authors explain the specification's reference implementation and show some portlet examples. (3,300 words; August 1, 2003)