subway

A subway is an underground transportation system that carries people from one place to another.

You might have seen subways in big cities like New York or London. In these places, subways are a common way for locals and visitors alike to get around without cars. People use their feet or hands to open the automatic doors of the train carriages and then board the subway. When they reach their destination, they usually follow signs pointing them towards exits, which lead out onto the street above ground again.