The article is dedicated to the overall presentation of contracts to which the law recognizes the power of enforcement, in a brief retrospect carried out through the Roman law and their evolution to the present day as they are found in the Civil Code or special laws that govern them. The contract is in effect, the conventional framework by which parties incur obligations and acquire rights in relation to each other, representing the materialization of the agreement of the parties and is only deemed validly concluded if the parties have expressed their consent freely and without undue influence. Contract partners are free to insert any clauses they want in the Covent signed, provided that they do not contravene to public order or morality. But the aim is to highlight both the power of the contract, and even more the importance of expressing the individual’s will on its fate. The importance of this legal act never contested, made the legislator invest it with the force of law between the contracting parties. So in cases expressly stipulated by the rules of law, this legal act has been given the benefit of enforcement, however without prejudicing in any way the principle of autonomy of will and without creating a contractual imbalance, privileges or discriminations.