Scrum is a management framework for software projects, which operates with a non-hierarchical organizational structure. The framework facilitates an iterative and incremental approach to product development, offering great flexibility in the face of customers who change their requirements during the development lifecycle. The methodology is sometimes referred to as a holistic or rugby approach (hence the name Scrum) as the project is implemented by a single cross-functional team, across multiple overlapping phases.
A Scrum team has some key defined roles which are always present: Scrum Master, Product Owner, and multiple members of the Development Team. Other roles which may be filled include Scrum Coach, Scrum Trainer and Scaled Scrum Expert. Certification is available for each of these roles.