European Territorial Cooperation (ETC), better known as Interreg, is a financing instrument of European regional development. Interreg has been designed in the framework of the European Cohesion Policy to intensify institutional cooperation across borders between regions located on European Union's internal and external borders, and regions within transnational areas. As regions of the EU Member States are facing similar issues not contained by borders, territorial cooperation stands out as a key tool in efficiently addressing socio-economic and environmental challenges. The overarching objective of European Territorial Cooperation (ETC) is to lessen the influence of national borders in order to promote a harmonious economic, social and cultural development of the Union as a whole. Interreg is built around three strands of cooperation: cross-border (Interreg A), transnational (Interreg B) and interregional (Interreg C). The current programming period 2014-2020 covers all 28 EU Member States, 3 participating EFTA countries (Norway, Switzerland, Lichtenstein), 6 accession countries and 18 neighbouring countries. The total allocation of Interreg V stemming from the European Regional Development Fund is EUR 10.1 billion, which represents 2.8% of the total of the European Cohesion Policy budget.