mToolkit is a set of convenient tools for testing OSGi-compliant bundles on OSGi Runtimes straight from the Eclipse Workbench. mToolkit's open source and commercial extensions deliver a plenty of powerful capabilities to the development environment of Eclipse related to management, emulation and tailoring of OSGi Runtime images.
The Eclipse environment supports pluggable units called plug-ins. The plug-in platform within Eclipse utilizes the OSGi technology - its core is an OSGi framework running the plug-ins which follow the OSGi bundle model. Across the user help of mToolkit, we'll use both terms, plug-ins and bundles, substitutively.
Eclipse, its Plug-in Development Environment (PDE) more specifically, offers a rich collection of tools for managing plug-ins (bundles) within the Eclipse IDE. It is recommended to develop a plug-in (bundle) by using an Eclipse plug-in project.
For more information about plug-ins and bundle in the context of Eclipse, refer to the "Plug-ins and bundles" from the Eclipse-delivered help.