Horde is both a piece of software and a project. The Horde Project comprises a set of Web-based productivity, messaging, and project-management applications, each of which is described below. The Horde Framework is a common code-base used by Horde applications, including libraries and a common user interface.
The Horde Framework doesn't do anything on its own; as a user, you will always be interacting with a Horde-based application.