A tender, to be valid, must satisfy the following essential requirements
(i) It must be unconditional.
(ii) It must be for the whole obligation and must not be in instalments, if the contract requires in full.
(iii) It must be by a person who is in a position and willing to perform the promise.
(iv) It must be at the proper time and place.
(v) It must be in proper form.
(vi) It must be made to a proper person i.e. to the promisee or his authorized agent.
(vii) In case of the tender of goods the promisee must be given a reasonable opportunity to inspect the goods.
(viii) It may be made to one of the several joint promisees.

(i) When its performance becomes impossible.
(ii) When the parties to it agree to substitute a new contract for it or to rescind or alter.
(iii) When the person at whose option it is voidable rescinds it.
(iv) When it is illegal

"When a person has made a promise to two or more persons jointly, then unless there is a contract to the contrary, the right to claim performance rests as between him and them, with them during their joint lives  and after the death of them with representatives of such deceased person jointly with survivors and after the death of last survivor, with the representatives of all jointly".

According to section 45 of Indian Contract Act Devolution means,"When a person has made a promise to two or more persons jointly, then unless there is a contract to the contrary, the right to claim performance rests as between him and them, with them during their joint lives: and after the death of them with representatives of such deceased person jointly with survivors,and after the death of last survivor, with the representatives of all jointly".

There are mainly two ways of performing a contract such as:
i) Actual Performance:
When the party has done what he had undertaken to do,it is called actual performance.In actual performance,the party is to fulfil all his obligations under the contract.
ii) Attempted Performance:
When the party offers to perform his obligation, it is not accepted by the promisee.A valid tender of performance is considered to be the performance of a promise.