This article is devoted to the notion of services in the EC law. The author underlines the importance of services in the present economy, employing 116 million people in the EU. He analyses art.50 of the EC Treaty and compares it with the definitions of services in the secondary law. The author identifies 3 phases of the services liberalization: 1) the elimination of discrimination, 2) the elimination of nondiscriminatory barriers, 3) the specific questions analysed in the jurisprudence and legislation. The article defines the subjective an objective scope of the freedom of movement of services. The last topic to be discussed relates to the relationship between the freedom of services and other freedoms.