Scrum means "crowd" and is a framework for the iterative and incremental development of digital products in a small team (ideally 5 - 10 people). Scrum Framework is described in the regularly updated Scrum Guide .
An iteration is a unit of time within a cycle, is called a sprint and usually lasts 14 days or a month. Every sprint is a loop with a beginning and an end and is therefore repetitive. It always starts with a planning meeting in which the goal of the sprint, namely the delivery of one or more increments, is planned. Each sprint ends with two consecutive meetings. The first of these is the so-called review. Here the completed increment is presented to the stakeholders. The review is followed by the retrospective, a meeting where only the team is present and reflects on their working methods and makes suggestions for improvements. Other working days of the teams start with a 15-minute daily stand-up. The Daily is used for consultation and the elimination of possible obstacles. The meetings are called ceremonies and are essential in Scrum.
Equally central are the three team roles of Scrum: Product Owner, Scrum Master, Team.
The product owner represents the interests of all those involved in the project (stakeholders) and is responsible for the end product. He determines the product requirements from the stakeholders, creates the product backlog (requirements broken down into user stories), is responsible for the return on investment (ROI) and creates the release plan.
The product owner prioritizes the product backlog based on business value points to ensure the most valuable features are developed first. Once the product owner has created the backlog, he presents it to the team in Sprint Planning. The team (developers) selects what they believe they can convert into a so-called increment of potentially deliverable functionality by the end of the sprint. This is how the Sprint Backlog is created. Since the team works in a self-organized manner, the development of the selected functions is left to them on their own responsibility.
The Scrum Master (like the Product Owner) is not part of the team. He removes obstacles for the team and ensures that the Scrum rules are followed. The Scrum Master is responsible for the Scrum process.
The tension between what the organization wants and what the team can do makes Scrum a very effective tool for producing high quality. In addition, the built-in self-organization creates an autonomy that is highly attractive for knowledge workers. In other words: the smarter the head, the less it likes to be told what to do or not to do. And developers are knowledge workers at a high to the highest level. In principle, Scrum attracts the best.
What is left out of Scrum:
The coordination and cooperation of several Scrum teams. This is a major disadvantage of Scrum.