Secretarial audit is the process of verifying a company's compliance with applicable laws. It is mandatory for listed companies and large unlisted public companies. The secretarial auditor, who is an independent company secretary, examines documents like minutes, statutory registers, and approvals to check for compliance. The secretarial audit report details any non-compliances found. It aims to protect shareholder interests and avoid legal issues due to lack of compliance. The secretarial auditor is appointed by the board of directors and files an annual report detailing the company's compliance with laws like the Companies Act, SEBI regulations, and other industry-specific laws. Non-compliance can result in penalties for both the company and its officers.