Metro systems are rapid transit networks designed to transport large numbers of people within urban areas. They typically consist of underground or elevated trains that run on fixed tracks, allowing for quick and efficient travel between different parts of a city. Metro systems help reduce traffic congestion and provide an eco-friendly alternative to cars. Many major cities around the world, such as New York City, London, and Tokyo, have well-established metro systems. These systems often feature multiple lines, each identified by a unique color or number, making it easier for passengers to navigate. Stations are strategically located to serve densely populated areas and key destinations.