Explanation:

When one of the parties to a contract has not given their consent freely or voluntarily, the contract becomes voidable, meaning that the affected party has the right to either affirm or void the agreement.

This situation arises when the consent is vitiated by coercion, undue influence, fraud, misrepresentation, mistake, or incapacity. Let us understand these concepts in brief:

1. Coercion: When a party is forced to enter into a contract under threat of physical violence or harm, the consent is said to be coerced. For example, if someone threatens to kill another person if they do not sign a contract, the consent is not free.

2. Undue influence: When one party takes advantage of their position of power or authority to influence the other party's decision, the consent is said to be undue. For example, if a doctor convinces a patient to undergo surgery that is not necessary for the patient's health, the consent is not free.

3. Fraud: When a party deliberately conceals or misrepresents material facts to induce the other party to enter into a contract, the consent is said to be fraudulently obtained. For example, if a seller misrepresents the quality of goods to make a sale, the consent is not free.

4. Misrepresentation: When a party innocently or negligently makes a false statement that induces the other party to enter into a contract, the consent is said to be vitiated by misrepresentation. For example, if a real estate agent falsely claims that a property has a clear title, the consent is not free.

5. Mistake: When both parties to a contract are mistaken about a material fact, the consent is said to be vitiated by mistake. For example, if both parties believe that a painting is an original when it is a fake, the consent is not free.

6. Incapacity: When a party is unable to understand the nature and consequences of the contract due to mental illness, intoxication, or minority, the consent is said to be vitiated by incapacity.

In conclusion, when the consent of a party is not free due to any of the above reasons, the contract becomes voidable, and the affected party has the option to affirm or void the agreement.