The Mistake is another important factor of free consent to avoid the contract. The mistake might be anything that occurred in the agreement itself. The mistakes are of two types-one is unilateral, and the other is bilateral mistakes.Unilateral Mistake: When a single party of a contract has mistaken the agreement knowingly or unknowingly it is considered as a unilateral mistake. Bilateral Mistake: Again, it has two divisions, namely common mistake and mutual mistake. A common mistake is a mistake that generally occurred in the norms of an agreement without prior knowledge. At the same time, mutual mistakes are considered as the misunderstandings of both the parties regarding the agreement and made mistakes innocently. This can be tried to resolve by making necessary modifications in the agreement.