Active help is the ability to invoke Eclipse code from on-line documentation. It is implemented by including some JavaScript in your documentation that describes a class that should be run inside the Eclipse platform.
For example, instead of writing, "Go to the Window Menu and open the message dialog," your on-line help can include a link that will open your application's message dialog for the user. Active help links look like hyperlinks in the on-line help.
Below is an active help link that opens the cheatsheet "Creating an Eclipse plug-in". We will take a look at how to create and reference your own actions.