• Definition: Agility is an ability enabling quick adaption to a changing environment.
• Manifesto for Agile Software Development
• The Agile Fluency Model
• SAFe, Story

Aspects:

• Complex software [1]: This implies a well understood problem domain. In contrast a pooly understood problem domain would be complicated software.
• Scrum is a framework, not a process, technique or method.[1]
• Iterative and incremental to optimize predictability and control risk.[1]
• Self organziation [1]: The team chooses the best way to do their work, they are not directed from outside the team in how they do their work.
• Product Owner
  • Manages the product backlog and is accountable for it.[1]
  • Clearly expressing product backlog items.[1]
  • Ordering the product backlog items to best achieve goals and mission.[1]
  • Ensuring that the product backlog is transparent, clear to all, showing what the Scrum Team will do next.[1]
  • Ensures that the Development Team understands the product backlog items to the level needed.[1]
  • Is one person and not a comitee.[1]
  • Is the sole person influencing on what the Development Team works.[1]
• Development Team
  • Only Development Team members create increments.[1]
  • Self-organization: The Development Team manage their own work. No one tells the Development Team how to turn product backlog items into increments.[1]
  • Cross-functionality [1]: The team has all competency needed to perform their work. The team does not depend on others from outside the team to do their work.
  • At least three and at most nine members [1]: For less than three members the framework might lead to more organizationals activities than necessary, for more than nine members create too much organizational overhead.
• Scrum Master
  • Ensures Scrum conformity: Helps to understand Scrum in theory, practices, rules and values.[1]
• The Sprint
  • Time-boxing: The duration of the sprint is fixed and defined beforehand. The duration should be constant. Duration of at most one month.[1]
  • Continuity: One sprints starts as soon as another ends.[1]
  • Consists of: Sprint Planning, Daily Scrums, development work, Sprint Review, and Sprint Retrospective.[1]
  • Consistency: No changes are made during the sprint which would endanger the Sprint Goal.[1]
  • Quality ensurance: The quality goals do not decrease.[1]
  • Cancelling
    • Only the Product Owner can cancel a sprint.[1]
    • A sprint is cancelled if the Sprint Goal becomes obsolete.[1]

References:

• [1] Scrum Guide