A responsibility assignment matrix (RAM), also known as RACI matrix or linear responsibility chart (LRC), describes the participation by various roles in completing tasks or deliverables for a project or business process. It is especially useful in clarifying roles and responsibilities in cross-functional/departmental projects and processes.
RACI is an acronym derived from the four key responsibilities most typically used: Responsible, Accountable, Consulted, and Informed.
Responsible - those who do the work to complete the task
Accountable - the one ultimately answerable for the correct and thorough completion of the deliverable or task, and the one who delegates the work to those responsible.
Consulted - those whose opinions are sought, typically subject matter experts; 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.