Exactly What is a Sale?
Basically, a sale is a transaction between a seller (that’s you) and a buyer (that’s your customer) which is an exchange of a product (that thing your business is doing over and over again) for payment (that’s usually money but also could be something else).
A sale is not complete until payment has been made. In most retail transactions the payment is made at the cash register so the sale is completed immediately. If you give credit, the sale is not complete until you have payment in hand.
You and your customer need to be in the same place to make a sale happen. The customer can come to you, or you can go to the customer, or you can both move and meet somewhere in the middle. This meeting can be physical and in real time - like a purchase in a retail store, virtual and real time - like a purchase on the internet, or remote in which case you will need some indication that a sale has indeed taken place. This can easily be accomplished with a purchase order which is a legal contract to pay for a product. But in each case, there is a handshake between the seller and the buyer that signifies the intention of a successful sale.