The Delhi Metro (Hindi: Dilli Metro), is a rapid transit system in the Indian city of Delhi that was built and is operated by the Delhi Metro Rail Corporation Limited (DMRC) The Delhi Metro was opened on December 24, 2002. It became the second underground rapid transit system in India, after Kolkata. The Delhi Metro has a combination of elevated, at-grade and underground lines. The Delhi Metro has won numerous awards for its environmentally friendly practices from many renowned organisations including the United Nations, and ISO. Delhi Metro was the first metro in the world to be ISO 14001 certified for environmentally friendly construction

Each train consists of four coaches and can carry up to 240 seated and 400 standing passengers. The trains operate at intervals of 3 to 4.5 minutes between 6:00 to 23:00. Coaches on all trains are well ventilated and air-conditioned at a temperature of 20~22°C. Trains operating within the network typically travel at speeds below 80 km/h, or 50 mph, and stop about 20 seconds at each MRTS station. The MRTS rolling stock are manufactured by ROTEM, relying on 1676 mm (5 ft 6 in) track gauge (broad gauge). As of 2008, the metro system has a total network length of 68 km, with 62 stations on 3 separate lines (13 underground, 48 elevated and 1 at-grade station). All metro stations and trains are monitored constantly by more than 1200 closed-circuit cameras, and specially trained Delhi Metro police are stationed at all stations and trains to deal with law and order issues in the system. Trains are at platform level with a small platform gap to allow easy movement of passengers.

The Delhi Metro is also one of the few metros in the world to have plainclothed metro-marshals on trains. Intercoms are provided in each train car for emergency communication between the passengers and the driver. Eating, drinking, smoking, and chewing of gum are prohibited in the entire system. Automated station announcements are recorded in Hindi and English. Many stations have services such as ATMs, food outlets, cafés and convenience stores