The primary purpose of a legal contract is to create a legally enforceable agreement between two or more parties. It defines the rights and obligations of each party and provides a framework for resolving disputes.

A valid contract requires the presence of all essential elements, including offer and acceptance, consideration, capacity, and legality. Offer and acceptance establish the terms of the agreement, consideration is the exchange of value between the parties, capacity refers to the legal ability to enter into a contract, and legality ensures that the contract does not violate any laws.

Implied contracts are not express contracts because they are not created through explicit words or actions. Instead, they are inferred from the conduct or circumstances of the parties.

A unilateral contract involves a promise by one party in exchange for an act by the other party, while a bilateral contract involves promises by both parties. In a unilateral contract, the offer is accepted by performance, while in a bilateral contract, the offer is accepted by a promise. In a unilateral contract, the consideration is executed, while in a bilateral contract, the consideration is executory.

The Doctrine of Consideration is the legal principle that states that a contract must be supported by consideration to be enforceable. Consideration is the exchange of value between the parties to a contract, and it can take various forms, such as money, goods, services, or a promise.

The Parol Evidence Rule is the legal principle that states that a written contract cannot be modified by a subsequent oral agreement. This rule is designed to prevent fraud and to ensure that the terms of a written contract are clear and unambiguous.

The Covenant of Good Faith and Fair Dealing is the legal principle that states that a contract must be performed in good faith. This principle requires parties to a contract to act honestly and fairly towards each other, even if the contract does not explicitly specify such a requirement.

The Doctrine of Frustration is the legal principle that states that a party cannot be held liable for a breach of contract if the breach was caused by an event beyond their control. This principle is often invoked in cases where unforeseen circumstances make it impossible or impracticable to perform the contract.

The Material Breach Doctrine is the legal principle that states that a contract can be terminated if one party materially breaches the contract. A material breach is a breach that goes to the heart of the contract and makes it impossible for the non-breaching party to receive the benefit of the bargain.

The Mistake of Fact Doctrine is the legal principle that states that a contract can be terminated if it is entered into under a mistake of fact. A mistake of fact is a belief that is not true and that is material to the contract.

The Mistake of Law Doctrine is the legal principle that states that a contract can be terminated if it is entered into under a mistake of law. A mistake of law is a belief that is not true and that is material to the contract.

The Duress Doctrine is the legal principle that states that a contract can be terminated if it is entered into under duress. Duress is a threat or coercion that forces a person to enter into a contract against their will.

The Undue Influence Doctrine is the legal principle that states that a contract can be terminated if it is entered into under undue influence. Undue influence is a situation where one party takes advantage of the weakness or vulnerability of another party to induce them to enter into a contract.

The Unconscionability Doctrine is the legal principle that states that a contract can be terminated if it is entered into under unconscionability. Unconscionability is a situation where one party takes advantage of the weakness or vulnerability of another party to induce them to enter into a contract that is grossly unfair or oppressive.

The Illegality Doctrine is the legal principle that states that a contract can be terminated if it is entered into under illegality. Illegality refers to a contract that is prohibited by law or that violates public policy.