Of the four basic liberties (the free flow of capital, labour, services and goods), whose achievement is defined as a fundamental goal of the European Union, posting is linked not to the free flow of labour but to the free flow of services.

The Directive has three different aspects (posting, secondment and loaning). A distinction between the three terms and their clear definition is critical:

secondment: An employer (company), under a contract between itself and a service recipient operating in the given Member State, sends an employee on its own behalf and under its own instructions provided that there is an employment relationship between the sending company and the employee during posting.

transfer: An employer sends employees to a site or company of the same group operating in another Member State provided that there is an employment relationship between the sending company and the employees during secondment.

loaning: An agency dealing in personnel loaning sends and employee to a company established or operating in another Member State provided that there is an employment relationship between the personnel loaning agency and the employee during the loan period.