A common market is a customs union with common policies on product regulation, and freedom of movement of all the three factors of production (land, capital and labour) and of enterprise. The goal is that movement of capital, labour, goods, and services between the members is as easy as within them.

Sometimes a Single Market is differentiated as a more advanced form of common market. In comparison to common a single market envisions more efforts geared towards removing the physical (borders), technical (standards) and fiscal (taxes) barriers among the member states. These barriers obstruct the freedom of movement of the four factors of production. To remove these barriers the member states need political will and they have to formulate common economic policies.

This is the fourth stage of economic integration.