A RACI matrix is a powerful project management tool that helps teams clarify roles and responsibilities within a project. It is a grid-like chart that outlines who is Responsible, Accountable, Consulted, and Informed for each task or decision. This matrix promotes effective communication, streamlines decision-making processes, and ensures accountability for project success. By clearly defining roles and expectations, the RACI matrix allows teams to work together efficiently and effectively towards a common goal.