The most effective backlogs follow the DEEP acronym. Each letter stands for a specific characteristic of a well-groomed backlog.
Detailed appropriately: Upcoming items in the backlog can be easily understood by team members, without being overly detailed. Alistair Cockburn describes backlog items as tokens promising a future conversation
Emergent: A product backlog should evolve, adding new items as we learn more about the problem space.
Estimated: A product backlog is a planning tool and helps organize development resources available. Therefore, each upcoming item should have an estimate of how long it will take to complete
Prioritized: Items on the backlog should be ranked with the most valuable items at the top.