A federation is a union of separate states or groups that agree to work together under a shared government while keeping some of their own powers and independence. Think of it like a team of teams: each member keeps its own identity and rules about local matters, but they all follow common rules about things that affect everyone.

The United States is a federation. Each state has its own government that makes decisions about schools, roads, and local laws, but all fifty states work together under the federal government in Washington, D.C., which handles things like national defense, printing money, and relations with other countries. When the Constitution was written, the states didn't want to give up all their power to a central government, so they created a federal system where power is shared.

You'll also see federations in sports. A sports federation is an organization that brings teams or clubs together under shared rules and competitions. Switzerland, Germany, and Canada are also federations where different regions maintain their own governments while cooperating on national issues.

The key idea: members of a federation remain somewhat independent but join together for strength and shared purposes they couldn't achieve alone.