A sale is the pinnacle activity involved in the selling products or services in return for money or other compensation. It is an act of completion of a commercial activity. The seller - the provider of the goods or services - completes a sale in response to an acquisition or to an appropriation or to a request.

There follows the passing of title (property or ownership) in the item, and the application and due settlement of a price, the obligation for which arises due to the seller's requirement to pass ownership. Ideally, a seller agrees upon a price at which he willingly parts with ownership of or any claim upon the item. The purchaser, though a party to the sale, does not execute the sale, only the seller does that. To be precise the sale completes prior to the payment and gives rise to the obligation of payment. If the seller completes the first two above stages of the sale prior to settlement of the price, the sale remains valid and gives rise to an obligation to pay.

Complex Sales, also known as Enterprise sales, can refer to a method of trading sometimes used by organizations when procuring large contracts for goods and/or services where the customer takes control of the selling process by issuing a Request for Proposal (RFP) and requiring a proposal response from previously identified or interested suppliers. Complex sales involve long sales cycles with multiple decision makers. Multiple stakeholders and stakeholder groups contribute to every complex sale.

Any product or service may become a complex sale. In some instances a complex sale occurs when the market is mature and the stakes high enough to warrant attention from a variety of stakeholders in the buying organization. In other instances a complex sales process is needed when the buyer has never had experience with the vendor, technology being sold, or if the solution is business critical or impacts the buying organization on a strategic level.

The series of filters, purchasing steps, and stakeholders involved are designed to reduce the risks associated with making the wrong buying decision. Marketing is the process by which companies create customer interest in products or services. It generates the strategy that underlies sales techniques, business communication, and business development. It is an integrated process through which companies build strong customer relationships and create value for their customers and for themselves.