Contract law is the part of civil law that studies the formation, characterization and effects of contracts.

In civil codification, as for example the Portuguese Civil Code or the Brazilian Civil Code, the law of contracts is normally treated as part of the law of obligations, due to the fact that the contract is considered, since Roman law, one of the main sources of obligations.

Contract can be considered as a bilateral legal transaction between the parties, creating legal duties that aim to achieve certain interests.