The following sentence is all about Eclipse RCP:
You may also be asking yourself why we have not used any of the Workbench’s extension points for defining actions. After all, Eclipse is all about declarative contributions.
This is a common question—when should an RCP application use the declarative Workbench extension points as opposed to simply creating the actions programmatically as in Hyperbola? In the context of a single small application, there is usually no need to use the extension point approach. In fact, an RCP application must minimally define a top-level menu structure using programmatic actions because without this, there would be no place to contribute actions declaratively.
What is the meaning of "contribution" and "contribute" in these sentences?