Sales are the activities involved in selling products or services in return for money or other compensation. It is an act of completion of a commercial activity.
The "deal is closed", means the customer has consented to the proposed product or service by making full or partial payment (as in case of installments) to the seller.
Academically, selling is thought of as a part of marketing, however, the two disciplines are completely different. Sales often forms a separate grouping in a corporate structure, employing separate specialist operatives known as salespeople (singular: salesperson). Sales is considered by many to be a sort of persuading "art". Contrary to popular belief, the methodological approach of selling refers to a systematic process of repetitive and measurable milestones, by which a salesperson relates his or her offering of a product or service in return enabling the buyer to achieve their goal in an economic way.