The Eclipse platform is basically a comprehensive integrated development foundation

The Eclipse platform is basically a comprehensive integrated development foundation (IDE) having no restriction on any programming paradigm. The platform itself is structured as subsystems and these sub-systems are running on top of Platform runtime. The following figure represents the high-level platform architecture of eclipse platform.

Here, the platform is built by wrapping around the set of Plug-ins. The plugins can be defined as the ordered collection of bundles of data /code which adds the functionality to the system and these functionalities can be assigned or added as code binaries, platform extensions. Extension points are named entities for contributing functionalities are defined by plugins.
If you consider the big picture, the Eclipse platform and other components comes under the ‘Eclipse SDK’ as shown in the figure below. It includes basic eclipse platform and two important tools which can be used for the extensive plug-in development. The two main tools are: (a)Java Development Tools (JDT), which is basically a fully integrated java development environment; (b)Plug-in Development Environment (PDE), which consists of streamlined tools for the extension of existing plugins as well as development of new plugin. Thus, JDT and PDE serves as the inevitable tools for the Eclipse SDK. The following figure shows where the JDT and PDE lies in the Eclipse SDK.