Purchase agreements for new aircraft are entered into between an aircraft manufacturer (as the seller) and a customer (as the purchaser). In the majority of circumstances, the customer will be an airline or an operating lessor but the customer can also be another entity such as a government body.

The terms of aircraft purchase agreements are often kept confidential between the aircraft manufacturer and the customer and are seldom revealed. The majority of such terms will not be disclosed to a financier of the customer, which is providing the customer with funding with respect to an aircraft to be purchased in accordance with the terms of that purchase agreement.

An aircraft manufacturer generally has a standard form purchase agreement that it will enter into with all of its customers. However, certain commercial terms will be negotiated between the parties and letter agreements are often entered into between the aircraft manufacturer and the customer to supplement the terms of the aircraft purchase agreement (see: Key provisions of a purchase agreement below).

Examples of aircraft manufacturers include: