What is world war 2 containment?

Answer 1

For the Allies it implied placing a limit on Axis expansion into strategic areas. Post-World War Two, it was the United State's push to restrict Communism whenever possible, usually through embargoes against existing communist countries.
Actually, Containment didn't begin until after WWII, because during WWII the U.S and U.S.S.R were allies, after WWII though, both began competing for supremacy, and the U.S was strongly opposed and afraid of communism, thus they invented containment, which, in short, is any action to prevent the spread of communism into other countries.