The umbrella standard — the auditor's objectives, ethical requirements, and the conduct of an audit per the SAs.
To obtain reasonable assurance about whether the financial statements as a whole are free from material misstatement, whether due to fraud or error, and to issue an auditor's report with the auditor's opinion.
SA 200 sits in the General phase of the audit. The Standards on Auditing are issued by the ICAI Auditing and Assurance Standards Board (AASB) and deemed to be prescribed by the Central Government under Section 143(10) of the Companies Act 2013. Compliance with SAs is mandatory for every audit conducted by a Chartered Accountant in India.
For authoritative text, refer to the ICAI AASB Compendium of Standards on Auditing at icai.org.