Scrum defines three main roles - the Product Owner prioritizes and owns the product backlog, the Scrum Master removes impediments and facilitates meetings, and the cross-functional self-organizing Team completes all the work. There are also three primary artifacts - the product backlog lists all product work, the sprint backlog lists work for the current sprint, and the burndown chart shows work remaining. Additionally, there are five activities - sprint planning creates the sprint plan, daily scrums are 15 minute status meetings, the sprint includes work completion, the review demonstrates work to the Product Owner, and the retrospective allows the team to improve.