Scrum is a lightweight framework that helps people, teams and organizations generate value through adaptive solutions for complex problems. Scrum consists of three roles (Scrum Master, Product Owner and Developers), five events (Sprint, Sprint Planning, Daily Scrum, Sprint Review and Sprint Retrospective), and three artifacts (Product Backlog, Sprint Backlog and Increment). Each component of Scrum serves a specific purpose and is essential to the successful usage of Scrum. Scrum is not a methodology, where you can "pick and choose" which parts of Scrum you think will work for your environment. Scrum is a whole, and each part of Scrum complements the others. Scrum is based on empiricism, which means that knowledge comes from experience and making decisions based on what is observed. Scrum employs an iterative, incremental approach to optimize predictability and control risk. Scrum is not like traditional processes but with self-management to replace Project Managers. Scrum is a different way of working that requires a shift in mindset and culture. Scrum promotes self-organization, collaboration, transparency, inspection and adaptation.
References:
Professional Scrum Product Owner II Certification
Understanding and Applying the Scrum Framework
[The Scrum Guide]