nyc, this question was answered just a few days back. Please check other threads before asking
Anyways, to answer you question, affidavits are sworn statements that the person signs in front of anybody who is authorized for this. In India, you can do this before a notary public (available near most gov offices where there are lawyers), or magistrates and above. Please note that in India the statement has to be typed on judicial stamp paper worth atleast Rs 15.