1.4 Types of Contract

The classification map (memorize as one answer): Validity: valid / void / voidable / unenforceable (Unit 6's categories); Formation: express / implied (the Code's written-verbal-conduct forms); executed / executory; unilateral / bilateral; Quasi contracts: obligations not from agreement but from law — the payment-by- mistake's recovery, the necessaries supplied to a minor, the finder's duties — "quasi" because contract-shaped without consent's base (Unit 7's full treatment); Contingent contracts: performance conditional on a future uncertain event (the insurance contract the paradigm) — valid, unlike the wagering agreement (void: the parties' only interest the stake — Unit 8's table); The nominate contracts: the Code Part V's special-contract chapters — sale, gift, lease, hire- purchase, loan, pledge, guarantee, indemnity, agency, jyala-majduri (the wage-work contract), carriage, deposit-and-safekeeping (Units 12–18's world); E-contracts: formed by electronic means — valid under the Electronic Transactions Act 2063's recognition machinery.