Subway trains are a type of public transportation that run underground or on elevated tracks in urban areas. They are designed to carry large numbers of passengers quickly and efficiently, connecting different parts of a city. Subway systems often have multiple lines, each identified by a unique color or number, making it easier for riders to navigate. These trains typically operate on a fixed schedule and have frequent stops at designated stations. Subway trains are powered by electricity, which allows them to travel smoothly and quietly compared to traditional diesel trains. Many major cities, such as New York City and Tokyo, have extensive subway networks that are vital for daily commuting.