Subways are underground or elevated rail systems designed to transport large numbers of passengers efficiently within urban areas. They are a vital part of public transportation in many cities, providing a fast and reliable means of travel that helps reduce traffic congestion and pollution. Typically, subways consist of multiple lines that connect various neighborhoods and key destinations, such as downtown areas, airports, and train stations. They are equipped with modern amenities and safety features, making them a popular choice for commuters and tourists alike.