The North–South Line (NSL) is a high-capacity Mass Rapid Transit (MRT) line in Singapore, operated by SMRT Corporation. Coloured red on the Singapore rail map, the line is 45 kilometres (28 mi) long and serves 27 stations, 11 of which, between the Bishan and Marina South Pier stations, are underground. It runs from Jurong East station, located in Western Singapore, to Marina South Pier station in the Central Area, via Woodlands station in northern Singapore. The line operates for almost 20 hours a day, with headways of up to 1 to 2 minutes during peak hours and 5 to 8 minutes during off-peak hours. All the trains on the North–South Line run with a six-car formation.

The Mass Rapid Transit system, locally known by the initialism MRT, is a rapid transit system in Singapore and the island country's principal mode of railway transportation. The system commenced operations in November 1987 after two decades of planning with an initial 6 km (3.7 mi) stretch consisting of five stations. The network has since grown to span the length and breadth of the country's main island – with the exception of the forested core and the rural northwestern region – in accordance with Singapore's aim of developing a comprehensive rail network as the backbone of the country's public transportation system, averaging a daily ridership of 3.4 million in 2019.