The RACI Model

Definition: a model used to help define who is responsible / accountable; The RACI model is built around a simple 2-dimensional matrix which shows the 'involvement' of Functional Roles in a set of Activities. 'Involvement' can be of different kinds: Responsibility, Accountability, Consultancy or Informational (hence the RACI acronym). The model is used during analysis and documentation efforts in all types of Service Management, Quality Management, Process- or Project Management. A resulting RACI chart is a simple and powerful vehicle for communication. Defining and documenting responsibility is one of the fundamental principles in all types of Governance (Corporate-, IT-Governance).

What does that mean?  All projects require management.  Simple enough.  This model is designed to define each level of management and required interaction on a project or application.  The four core levels of involvement attempt to define who should know what about the project/application/system.  Each level has more direct interaction than the previous level.

The levels are defined as:

Responsible

Those who do the work to achieve the task. There is typically one role with a participation type of Responsible, although others can be delegated to assist in the work required (see also RASCI below for separately identifying those who participate in a supporting role).

Accountable (also Approver or final Approving authority)

Those who are ultimately accountable for the correct and thorough completion of the deliverable or task, and the one to whom Responsible is accountable. In other words, an Accountable must sign off (Approve) on work that Responsible provides. There must be only one Accountable specified for each task or deliverable.

Consulted

Those whose opinions are sought; and with whom there is two-way communication.

Informed

Those who are kept up-to-date on progress, often only on completion of the task or deliverable; and with whom there is just one-way communication.

Very often the role that is Accountable for a task or deliverable may also be Responsible for completing it (indicated on the matrix by the task or deliverable having a role Accountable for it, but no role Responsible for its completion, i.e. it is implied). Outside of this exception, it is generally recommended that each role in the project or process for each task receive, at most, just one of the participation types. Where more than one participation type is shown, this generally implies that participation has not yet been fully resolved, which can impede the value of this technique in clarifying the participation of each role on each task.

Note: I stole most of that from Wikipedia.