Essential Contract Types and Legal Definitions
Contract Definition
An act by which one party undertakes to another to give, do, or not do something.
Unilateral Contract
One in which one party undertakes to another to give, do, or not do something.
Bilateral Agreement
One where the contracting parties mutually undertake obligations.
Imperfectly Synallagmatic Contracts
Contracts initially appearing unilateral but later generating obligations for the party originally not bound.
Plurilateral or Associative Agreement
An agreement with two or more parties where the benefits for each are aimed at achieving a common goal.
Gratuitous Contract
One that seeks only the benefit of one party, while the other party bears the burden or obligation without equivalent benefit.
Onerous Contract
One that seeks the utility of both contracting parties, with each party receiving a benefit in exchange for their obligation.
Commutative Contract
One in which each party undertakes to give or do something considered equivalent to what the other party must give or do in return.
Aleatory Contract
One where the economic effects or outcome depend on an uncertain event.
Principal Contract
One that subsists by itself, without needing another agreement.
Accessory Contract
One that aims to ensure the fulfillment of a principal obligation and cannot subsist without it.
Real Contract
One that requires the delivery (tradition) of the thing to which it refers as a necessary condition for its perfection.
Solemn Contract
One that requires adherence to specific legal formalities for its validity, without which it produces no civil effect.
Consensual Contract
One that is perfected by the mere consent of the parties.
Nominate Contract
A contract specifically regulated by law.
Innominate Contract
A contract not specifically regulated by law.
Instantaneous Performance Contract
One in which the obligations arise and are typically fulfilled immediately upon formation.
Successive Performance Contract
One in which the obligations are fulfilled over a period of time.
Individual Contract
One whose formation requires the expression of will from each person who becomes legally bound by it.
Collective Contract
One that binds people who did not personally participate in its creation, did not consent, or even dissented (e.g., collective bargaining agreements).
Freely Discussed Contract
One in which the parties have negotiated the terms, content, and clauses.
Adhesion Contract
One in which one party drafts the clauses, and the other party simply accepts or adheres to those terms without substantial negotiation.
Directed Contract
One that is regulated and controlled by the government regarding its formation, implementation, or duration, or where public authority sets certain terms or conditions.
Forced Contract
One where the law obliges parties to enter into it, or it is deemed concluded by law under certain circumstances.
Preparatory Contract (or Framework Contract)
One in which parties establish the terms or general conditions for future contracts between them.
Subcontract
A contract where one party (contractor) transfers duties or obligations from a previous (main) contract to another party (subcontractor). The original contractual relationship typically remains.
Self-Contract (Autocontrato)
A legal act where one person acts in multiple capacities, such as representing both parties to the contract, or acting for themselves and as a representative of another party.
Contract for a Person to be Named
One in which a party reserves the right to later designate the person who will retroactively acquire the rights and obligations arising from the contract.
Contract for Whom It May Concern
One entered into where one party is initially unidentified but is expected to be determined or identified later.
Promise Contract (Preliminary Contract)
A written agreement where parties obligate themselves to conclude a future contract (the promised contract) within a specified term or upon a condition. The essential elements of the future contract must be specified, leaving only the formal execution (e.g., delivery of the item or required formalities) for its perfection.
Sales Contract
A contract in which one party (the seller) agrees to transfer ownership of something to another party (the buyer), who agrees to pay a price, typically in money.
Earnest Money (Arras)
An amount of money or other movable property given as security for the conclusion of a contract, as a sign of commitment, or as part payment of the price, as agreed by the parties.