In Quality Term, AQL stands for Acceptable Quality Level.
It means in sample based product inspection system, how minimum defectives goods are acceptable in an order as per contract with a customer.
AQL level very depending on severity of defects. like, few customer accept AQL 4.0 for minor defects and in the same order AQL 2.5 is used for major defects.
At present, when a customer imports goods from other countries follow sample based inspection, that is AQL. To use AQL based inspection auditor use AQL Chart that is originated by ANSI.