How does common market unite Europe?

Answer 1

By creating a larger market for their economic trade system, tariff free with the free movement of labor and capital thus strengthening their economy and creating a common identity to some level through the deepening of regional integration.

Answer 2

The EU has developed a single market through a standardised system of laws which apply in all member states, ensuring the free movement of people, goods, services, and capital.[13] It maintains common policies on trade,[14] agriculture, fisheries[15] and regional development.[16] Sixteen member states have adopted a common currency, the euro, constituting the Eurozone.