Sections 68-72 of The Indian Contract Act, 1872 deals with Quasi Contracts. Quasi means apparently but not really. Obligation between the parties isn't contractual but one which is treated as contractual through regulation. Courts create quasi-contracts to defend the unjust enrichment of the parties in dispute over the price of goods or services. Consequently, the duty of one birthday celebration to some other imposed by way of law independently of an agreement among the parties.

Claim for Necessaries supplied to incapable person (Section 68) - if a person, incapable of stepping into a contract, or all people who are legally sure to guide, is supplied by another man or woman with necessaries perfect to his condition in lifestyles, the person who has furnished such resources is entitled to be reimbursed from the belongings of such incapable character. Example-a, a tradesman, leaves items at b’s house via mistake. b treats the goods as his very own. He's certain to pay A for them.
People incapable of moving into the contract-

A minor
The character of unsound mind
Man or woman disqualified with the aid of the regulation
Reimbursement of person paying money due by another (section 69) - A person who's interested in the price of money which some other is certain by regulation to pay, and who therefore can pay it, is entitled to be reimbursed via the alternative. Example- b holds lands in Bengal, on a rent granted by way of a zamindar. The revenue payable using a lot to the authorities, being in arrear, his land is advertised for the sale through the authorities. Below the revenue law, the outcome of such sale could be the annulment of b’s rent. B, to save you the sale and the consequent annulment of his very own rent, can pay to the authorities the sum due from A. A is to make corrections to b the quantity so paid.
The obligation of the person enjoying non-gratuitous act (Section 70) - Wherein someone lawfully does something for some other man or woman, or offers something to him, no longer proceeding to accomplish that gratuitously, and such different character enjoys the gain thereof, the latter is sure to make repayment to the previous in recognize of, or to repair, the factor so finished or introduced. Example- A, a tradesman, leaves items at b’s house by way of mistake. b treats the products as his own. He's certain to pay A for them.
Responsibility of finder of goods (segment 71) - a person who unearths items belonging to another, and takes them into his custody, is a challenge to the same responsibility as a bailee.
Responsibility of person to whom money is paid, or a thing is delivered by mistake or under coercion (section 72) - a person to whom cash has been paid, or something delivered, via mistake or below coercion, must repay or go back it. Example- A and B mutually owe a hundred rupees to c. An alone can pay the quantity to c, and b, no longer understanding this reality, pays a hundred rupees-over again to c. c is bound to pay off the quantity to b.