An obligation has three elements:

Creditor: Creditor is the party who is entitled to request the consideration. In a donation contract, the parties are named as the donor and the donee. Donee is the creditor. Whereas in a sales contract, the parties are named as the seller and the buyer and both of them are creditors, since sales contract is a contract in which both of the parties are under a burden of a consideration. The “seller” is under the liability of delivering the sold goods to buyer, the “buyer” is liable to pay agreed price to seller, in return.

Debtor: Debtor is the party who is bound to perform a certain act given as consideration. In a donation contract, the donor is the debtor, whereas in a sales contract both the seller and buyer are debtors.

Consideration: Consideration is an act, which the debtor is obliged to perform as the content of her obligation. It may be an act of giving something, like in sales contracts, giving the good and giving the payment in return. It may be an act of doing something, like in employment contract-employees cleaning the building, or it may be an act of refraining from doing something, like in an agreement of restraint of trade.

Thus, in a sales contract, both the buyer and the seller are the creditors and also the debtors.