Scrum is an iterative and incremental agile software development methodology for managing product development.
It defines “a flexible product development strategy where a 
development team works as a unit to reach a common goal”, challenges assumptions of the “traditional, sequential approach” to product development, and enables teams to self-organize by encouraging physical co-location or
close online collaboration of all team members, as well as daily face-to-face communication among all team members and disciplines in the project.
That person creates a ranked product backlog that the cross-functional team takes.The team, which has all the roles it requires, works off the backlog and creates features, producing shippable product on a regular basis.