The ARB, or Architects Registration Board, is a UK-based organization responsible for regulating the architecture profession. Its primary role is to maintain a public register of qualified architects and ensure that standards of education and practice are maintained. 

The ARB sets the criteria for architecture education and qualifications, oversees the examination process for registration, and has the power to act if an architect's conduct or competence falls short. 

By doing so, the ARB helps to protect the public and ensure the profession maintains high standards. For architects, registration with the ARB is a mark of professionalism and credibility, demonstrating that they meet the national standards for education, training, and practice.