Introduction to the mechanics of Scrum

Here are the basic characteristics and features of Scrum:

• Planning style: Empirical/adaptive
  
• Delivery style: Iterative/incremental
  
• Iteration length: Ranges between 1 and 4 weeks; a length within this range is initially chosen by the team and then fixed. The most popular is 2 weeks.
  
• Values: Commitment, courage, focus, openness, and respect
  
• Roles: Product Owner, Scrum Master, Development Team
  
• Team size: small, 5-9
  
• Artefacts: Product Backlog, Sprint Backlog, Sprint progress tracking
  
• Events: Sprint Planning, Daily Scrum, Sprint Review, Sprint Retrospective
  
• Special features: All events are time-boxed
  
• Lacks: A product/project/feature initiation phase and doesn't specify technical practices

There are three roles in Scrum: the Product Owner, the Scrum Master, and the Development Team, which are defined as follows:

Team size is essential in a Scrum. Face-to-face communication is preferred by Agile teams; it's open and has a high bandwidth. The larger the team gets, the harder it becomes for each team member to know everything that is going on. 

Scrum recommends a team of no fewer than five and no more than nine. Fewer than five (which includes the Product Owner and Scrum Master) and it's believed that the team will be limited in what it will be able to achieve. More than nine and the team's communications will become strained, and information may fall through the cracks. 

The Scrum Guide defines three artifacts—Product Backlog, Sprint Backlog, and Increment:

Scrum uses an incremental approach to delivering. It achieves this by working in iterations known as Sprints. The recommended length for a Sprint is between a minimum of 1 week to a maximum of 4 weeks. Most teams opt for a 2-week Sprint:

The Sprint isn't the only aspect of Scrum that has a time limit, also known as time-box. All of events, such as Sprint Planning, the Daily Scrum, and so on, are also time-boxed. The aim of time-boxing an event is to ensure focus is maintained. The time-box for each event is proportional to the length of the Sprint and is set out in the Scrum guidelines.