I want details about power of attorney?

A power of attorney (POA) or letter of attorney in common law systems or mandate in civil law systems is an authorization to act on someone else's behalf in a legal or business matter. The person authorizing the other to act is the principal, grantor, or donor (of the power), and the one authorized to act is the agent or attorney-in-fact[1] or, in many common law jurisdictions, simply the attorney.