1. the promisor himself
2. agent
3. representatives

According to Para 2 of Section 40, the promisor may employ a competent person such as agent to perform the promise, if the contract is not formed on personal condition. That person is called an agent.

There are mainly two ways of performing a contract such as:
1. Actual performance
2. Attempted performance

Those persons who have made a joint promise, then unless a contrary intention appears in the contract, all such persons, during their joint lives and after the death of the last survivor, representatives of all, jointly must fulfil the promise are called joint promisors.
Benefits:
1. The promises are mutual. So both the parties are benefited.
2. Reciprocal promises maybe independent (or) dependent (or) concurrent. So flexibility will be there.

A valid tender of performance is considered to be the performance of a promise.

Appropriation means application of payments-The question of appropriation of payments arises when a debtor owes several debts to the same creditor and makes a payment that is not sufficient to discharge the whole indebtedness.
1. Appropriation of Payments:
1. Sometimes, a debtor owes several distinct debts to the same creditor and he makes a payment which is insufficient to satisfy all the debts.
2. In such a case, a question arises as to which particular debt the payment is to be appropriated.
3. Section 59 to 61 of the Act lay down following rules as to appropriation of payments which provide an answer to this question.
2. Appropriation as per express instructions:
1. Every debtor who owes several debts to a creditor has a right to instruct his creditor to which particular debt, the payment is to be appropriated or adjusted.
2. Therefore, where the debtor expressly states that the payment is to be applied to the discharge of a particular debt, the payment must be applied accordingly.
3. For Example X owes Y three distinct debts of Rs.20,000, 30,000 and 50,000. A sends Rs.50,000 and instructs Y that the payment should be appropriated against the third debt. He is bound to appropriate the payment against the third debt only.
3. Application of payment where debt to be discharge is not indicated [60]:
1. If section 60 is attracted, the creditor shall have the discretion to apply such payment for any lawful debt which is due to him from the person making the payment.
2. For Example P owes to Q, among other debts, the sum of Rs.10,000. Q writes to P and demands payment of this sum. P sends to Q Rs. 10,000. This payment is to be applied to the discharge of the debt of which Q had demanded payment.
4. Application of payment where neither party appropriates [61]:
The payment shall be applied in discharge of the debts in order of time whether they are or are not based by the limitation Act 1963, if the debt are of equal standing (i.e. payable on the same date) the payment shall be applied in discharge of each of these debt proportionately.

It is only the promisee for whom the contract is performed. Only the promisee can demand the performance of the promise under a contract. For Example: X promises Y to pay Z Rs. 10,000/. X does not pay the sum to Z. Here Z cannot bind X for the payment. It is only promisee Y who can enforce the promise against the promisor X.
Of course, there are certain special cases, where a third party can enforce a promise though he is not a party to the contract For example in respect of trust, marriage settlement, etc. In case of death of promisee, the representative appointed by him can ask for the performance of the promise under a contract.