The Eclipse platform's help facilities provide you with the raw building blocks to structure and contribute documentation to the platform. It does not dictate structure or granularity of documentation. You can choose the tools and structure for your documentation that suits your needs. The help plug-in allows you to describe your documentation structure to the platform using a table of contents (toc) file.
Your plug-in's online help is contributed using the org.eclipse.help.toc extension point. You can either contribute the online help as part of your code plug-in or provide it separately in its own documentation plug-in.
Separating the documentation into a separate plug-in is beneficial in those situations where the code and documentation teams are different groups or where you want to reduce the coupling between the documentation and code.
Advanced features of the help system include context-sensitive help with reference links and the ability to invoke platform code from the documentation. A help browser lets you view, print, and search your documentation. Since 3.1, the new Help view adds dynamic help and federated information search capability.
The best way to demonstrate the contribution of help is to create a documentation plug-in.