Eclipse is a IDE ( Integrated Development Environment ) for creating Java Applications. It has an editor, compiler, debugger, deployment environment and all other development tools in one Application. But if you wish to integrate Eclipse to other systems and APIs, we can create our own Eclipse plugin. Plug-in is an add-on tool to the already existing Eclipse IDE.
You need to have two files to as a requirement for plug-in development.
1. Manifest file – MANIFEST.MF contains all the required libraries as runtime dependencies for this plug-in.
2. plugin.xml – This file has the contents on how this plug-in is dependent/extended on another plug-in. Extension points are the needed extensions taken from the bundle libraries defined in the MANIFEST.MF file.
more details is described in this site