The single market is the EU’s greatest achievement. It is an area without internal borders in which the free movement of goods, persons, services and capital is, in principle, guaranteed. To bring this into being, EU legislators have adopted hundreds of directives to remove technical, regulatory, legal and cultural barriers within the Union. The creation of the internal market encouraged EU Member States to liberalise the monopolistic public utility markets that had been protected until that point. By aligning their national laws, Member States set about harmonising rules and standards within the EU. Examples of this can be seen in the mutual recognition of diplomas, in public procurement, intellectual property and financial supervision.