A portlet is a Java technology based web component, managed by a portlet container, that processes requests and generates dynamic content. Portlets are used by portals as pluggable user interface components that provide a presentation layer to Information Systems. From: Java(tm) Portlet Specification 1.0 (JSR-168)
A portal-based application that supports autonomous functionality. Liferay Portal ships with over 50 useful, pre-bundled portlets.
A mechanism used to readily integrate content, applications and processes into portals. Portlets provide a low-level, point-to-point integration approach by accessing program application programming interfaces, Structured Query Language statements, Web services and more. Web services and Java provide mechanisms for enabling portlets written for one vendor's portal to run unchanged in another vendor's portal. Emerging standards to enable portlet interoperability include Java Specification Request (JSR) 168 and Web Services for Remote Portlets (WSRP). See