DAD (Disciplined Agile Delivery) is a process-oriented, learning, and solution-oriented framework published by Scott Ambler in 2007 that was created to fill the process gaps that were not defined in Scrum. The key difference between DAD and Scrum lies in the roles: DAD has a team leader role in addition to the product owner and team member roles, and there are also secondary roles in DAD such as independent testing expert, domain expert, technical expert, and adapter (integrator).