Definition:
ADKAR is an acronym that forms five building blocks that bring about successful change. These letters stands for Awareness, Desire, Knowledge, Ability and Reinforcement. ADKAR model was developed by Jeff Hiatt in 2003.
Employees usually resist Organizational Change, where ADKAR model is a change management tool to help identify why change is difficult, why some changes succeed or failed. This model is mainly intended to be a coaching and change management tool to help and assist employees through the change process within organizations.
Further Reading:
Book:SUCCEEDING WITH AGILE Software Development Using Scrum by Mike Cohn
Book: How to Change the World by Jurgen Appelo