This industry comprises establishments primarily engaged in providing human resources and human resource management services to client businesses. Establishments in this industry operate in a co-employment relationship with client businesses or organizations and are specialized in performing a wide range of human resource and personnel management duties, such as payroll, payroll tax, benefits administration, workers' compensation, unemployment, and human resource administration. Professional employer organizations (PEOs) are responsible for payroll, including withholding and remitting employment-related taxes, for some or all of the employees of their clients, and also serve as the employer of those employees for benefits and related purposes.