Human resource management encompasses activities related to managing an organization's workforce, including recruiting, selecting, developing, and compensating employees. Theories of HRM have evolved over time from a classical focus on tasks and control to a humanistic focus on relationships and participation. Modern HRM theories aim to integrate concerns for both production and people. Key humanistic theories include human relations theory based on the Hawthorne Studies, Barnard's emphasis on communication and cooperation, and McGregor's Theory Y of positive human motivation. Human resources theory, including Likert's systems model and Blake and Mouton's managerial grid, further developed these ideas.