This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Somin, Eclipse comes with some functionality built in. Everything else is available as a "plugin". This means you can take an external jar file and use it with Eclipse. In this way it is plugged in. Of course, this jar file must be developed in a certain way. There are whole books on developing plugins. But to use one, all you have to do is unzip it in the plugins directory.