Internal control is defined as a process that helps an organization achieve its objectives through effective and efficient operations, reliable financial reporting, and compliance with laws and regulations. The objectives of internal control include avoiding inefficiency, ensuring accurate books of accounts, and measuring how well business policies are implemented. Internal control is important for protecting assets, addressing financial statement assertions, and establishing company practices, though it has limitations such as collusion, human error, and management override. Internal checks are accounting procedures where routine transactions are handled by multiple employees to detect errors through cross-checking work. Criteria for good internal checks include dividing work, rotating jobs, authority levels, separating custody from recording duties, and accounting controls.