Seoul Metropolitan Subway

Seoul Metropolitan Subway, often called the Seoul Subway, is a rail transit system of underground trains and commuter trains that connects Seoul to nearby suburbs.

The system has 22 lines that are named after numbers (Line 1, Line 2, all the way to Line 9). It also has Gyeongui Line, Bundang Line, Shinbundang Line, A'REX, Jungang Line, Gyeongchun Line, Suin Line, Incheon Line 1, Everline, and U Line.
Since 2010, all stations have smartphone-like 46-inch touchscreen kiosks so passengers can look at maps, make free phone calls, and find tourist information. All lines use special RFID cards, such as T-money, or NFC technology where passengers can pay fees.