The term contract refers to an agreement among multiple parties that is mutually binding. The parties typically are referred to as the buyer and the seller. The seller refers to the party with a specific resource, product, service, or other item which they are providing to the buyer, who is the purchaser of said item. The contract, once signed by both parties, binds both parties to a pre-defined set ofterms which dictate all aspects of the arrangement. The terms covered in the contract are typically tremendously detailed and numerous, and this is to the benefit of the seller as well as the buyer, as it helps to make sure that both parties are on the exact same page, and prevents surprises when the time for product delivery arrives.Specific items covered in the contract will typically include cost of the services in question, the period of time in which the services will be delivered, and specific features, components, or characteristics that are to be included in the final deliverable.
This term is defined in the 3rd and the 4th edition of the PMBOK.