The Eclipse Platform is an open and extensible platform for anything and yet nothing in particular. It provides a foundation for constructing and running integrated software-development tools. The Eclipse Platform allows tool builders to independently develop tools that integrate with other people's tools so seamlessly you can't tell where one tool ends and another starts.
This package contains Java Development Tools. These provide a powerful Java IDE along with several editors, a refactoring engine, Ant and JUnit integration, a debugger, and many more features.