Scrum is an agile methodology for managing software development projects that emphasizes iterative development, self-organizing cross-functional teams, and adaptive planning. It consists of sprints where a team works to complete user stories from the product backlog, conducting daily stand-ups, sprint reviews, and retrospectives. Key roles include the product owner who manages the backlog, the scrum master who facilitates the process, and team members who do the work. The agile manifesto values individuals and interactions, working software, customer collaboration, and responding to change over processes, tools, contract negotiation, and documentation.