Метрополитен, commonly known as the subway, is an underground train system that provides efficient public transportation in urban areas. It allows passengers to travel quickly across cities, avoiding traffic congestion. Many major cities around the world, such as New York City, London, and Tokyo, have extensive metro systems that connect various neighborhoods and key locations. The first metro system was opened in London in 1863, and since then, many cities have developed their own networks. Metropolitens typically consist of multiple lines, each identified by a unique color or number, making it easy for riders to navigate. They are an essential part of urban infrastructure, promoting sustainable transportation.