Chapter 3 identifies the defining features of the internal market – the characteristics that distinguish the internal market from any single market constellation and serve as a possible benchmark for determining the degree of homogeneity in the expanded internal market. The Chapter focusses on the principles that form the economic core of the internal market, such as the four fundamental freedoms and competition policy, and their interaction with horizontal provisions, fundamental rights and EU citizenship. In addition to looking at the internal market as a whole, the Chapter also explores whether the specific sectors of the internal market feature distinctive cores.