Agile Overview → Work Items → Epics
An epic is a very large work item that cannot be worked on by the team during any single sprint. It must be broken down into a smaller work item (stories) before it can be discussed in a planning meeting and before any related work is moved into a release or sprint backlog.
Epics represent how your organization plans to deliver business value at the product level. Epics often map to key features outlined in the product roadmap (what your team plans to deliver over the next 2-4 releases). Sometimes an epic itself is used to represent a feature that is worked on during a single release. Epics are discussed during product planning and are broken down into smaller collections before being moved into release planning. In the product backlog, epics can be grouped by major themes, such as automation, user interface, documentation, and so on.