Quasi contracts (Sections 68-72) are obligations imposed by law even without agreement. These cover situations where one party receives benefit from another without contractual relationship. Types: (1) Money paid by mistake—recovery allowed if paid under error; (2) Non-gratuitous act—recovery for necessaries supplied to person incapable of contracting; (3) Goods delivered by mistake—recovery available; (4) Benefit from act without consent—recovery if done with intention beneficiary would pay. Requirements: (1) Benefit conferred; (2) With knowledge/reasonable expectation of payment; (3) Recipient accepting benefit; (4) No agreement otherwise. Quasi contract differs from contract: No agreement but law implies obligation. Case law: Illet v. Illet establishes quasi contract principles. Distinction from unjust enrichment: Quasi contracts prevent unjust enrichment by implying obligation to pay. For accountants, quasi contract applies to unsolicited services rendered in emergency; understanding limits protects practice. Exam tip: Identify benefits conferred without agreement; apply quasi contract when agreement absent but obligation should exist.