Contract Law is an essential part of Civil Patrimonial Law. It studies the rules regarding the general theory of contracts and civil contracts in particular. In this sense, we analyze the concept of contract, its essential elements, its effects and inefficacy. With regard to each contract, we study the contents thereof, and in particular, the rights and obligations of the contracting parties. The main contracts to be studied are: the contract of sale, donation, lease of things, rural and urban leases, the contract of provision of services, construction contracts and partnership, among others. We are within a part of the Civil Law that has a scope beyond it, because it extends to other fields of Law, specially Commercial Law and Labour Law. When studying Contract Law we have to take into account the European Law of contracts because there is a tendency towards its uniformity in the European Union. It also has to be studied from the protection of consumer¿s perspective, making a special reference to the conclusion of contracts with general conditions.