The Commonwealth of Independent States (CIS) is a group of countries (also known as member states) in Europe and Asia that used to be a part of the same country. This country was the Soviet Union, and it split into several different countries. All of these countries are members of the CIS. The CIS works together to promote peace, friendly relationships and economic ties between the countries. They also help each other to solve problems and make decisions. The CIS is like a big group of friends who help each other out.