Seller decides to sell object. Buyer offers to buy object. Seller and buyer agree on price, delivery. Seller transfers object to buyer. Buyer pays price to seller.
Buyer owns object.
Jim is the buyer. Jim probably payed some money to Joe. At some point, Joe decided to sell the Mustang. At some point, both Jim and Joe must have agreed on a price and agreed how the Mustang would be delivered. Although the framework above appears simple, there are a number of extensions that it must have that make it really useful.