A person with long administrative experience & knowledge of accounts is appointed.
Holds office for 6 yrs or till 65 yrs of age.
The President can remove him only on the recommendation of the 2 houses of Parliament (as in case of judge of Supreme Court).
Powers:
He is the guardian of the public purse. His duties are to audit the accounts of the Union and the States and to ensure that nothing is spent out of the Consolidated Fund of India or of the States without the sanction of the Parliament or the respective State Legislature.
He submits an audit report of the Union to the President who shall lay it before the Parliamentary and the audit reports of the States to the respective Governors who shall lay it before the respective State Legislature.
In short the CAG acts as the custodian & trustee of public money.