Nationalization is when private property or industry is taken over by the government. Countries usually choose to nationalize portions of a specific industry, and they do it for different reasons.
If an oil-producing country’s oil drilling operations are owned mostly by foreigners, for example, the government might choose to nationalize all drilling operations to get rid of the excessive foreign influence.
Sometimes countries with struggling industries choose to nationalize certain sectors of the economy so that government resources can be used to help those industries develop. When the U.S. government spent money bailing out big banks during the economic crisis, some people thought it was a step toward nationalizing the financial sector.