A backlog is a list of tasks or features that are desired for a product, but have not yet been scheduled for development. Backlogs are often used in agile development processes, and can include items such as user stories, technical tasks, or defects. The backlog is a living document that is continually updated and prioritized based on the needs of the product and the team. By maintaining a backlog, product teams can better manage their workload and ensure that they are working on the most valuable tasks at any given time.