A more thorough explanation:

The Outer Space Treaty is a law made by the United Nations that says no country can claim ownership of any planet or moon. It also says that no country can put weapons or military bases in space. The treaty applies international law and the United Nations charter to space.

For example, if a country wanted to claim ownership of the moon, they would not be allowed to do so because of the Outer Space Treaty. Also, if a country wanted to put a military base on Mars, they would not be allowed to do so because of the treaty.

The Outer Space Treaty is important because it helps to keep space peaceful and open for exploration by all countries.