The RACI matrix is a type of responsibility assignment matrix (RAM) which is used to delegate tasks, activities, milestones, or decisions to project team members in order to clarify expectations on their level of participation. Each team member is designated a role in the RACI hierarchy which is an acronym that stands for (Responsible, Accountable, Consulted, Informed).
Responsible members are persons whose contributions and efforts result in a tangible deliverable or completed task. Responsible participants work "in the trenches" and have a broad knowledge base of the task at hand. For each task or activity, only one team member should be assigned the responsible role.
Accountable members (also referred to as Approvers or Approving Authorities) are individuals whose approval of the work is required before the task or activity is considered completed. Accountables are the people in the spotlight -- the first ones called if something goes wrong and the first ones showered with praise for the successes.
Consulted members are persons who play an indirect or advisory role and whose contributions are in the form of special knowledge or expertise. There can be multiple consultants, but their input is essential to moving the task forward to successful completion.
Informed members are persons who should be kept in the loop even though they have no direct or indirect role in the activity. These people need to be notified of important decisions and included on the list to receive regular status reports.