The freedom to provide services is a fundamental right set forth in the Treaty on the Functioning of the European Union (TFEU, Art. 56 to 62). It is one of the four fundamental freedoms of the European single market. The other three are the free movement of goods, free movement of workers, and the free movement of capital and payments. It offers providers of industrial, commercial, non-industrial, and freelance services free access to the service markets of all member countries of the European Union.

Source: Wikipedia, edited