The Delhi Metro is a mass rapid transit (MRT) system serving Delhi and its satellite cities of Ghaziabad, Faridabad, Gurugram, Noida, Bahadurgarh and Ballabhgarh, in the National Capital Region of India. The Delhi Metro has been instrumental in ushering in a new era in the sphere of mass urban transportation in India. The swanky and modern Metro system introduced comfortable, air-conditioned and eco-friendly services for the first time in India and completely revolutionized the mass transportation scenario not only in the National Capital Region but the entire country. It is by far the largest and busiest metro rail system in India and the second oldest after the Kolkata Metro.
The network consists of 10 colour-coded lines serving 253 stations in Delhi with a total length of 348 kilometres (216 mi) and has a full reach of 285 stations with a total length of 389 kilometres (242 mi) when including the Gurugram Metro and Noida Metro. The system has a mix of underground, at-grade, and elevated stations using both broad-gauge and standard-gauge. Delhi Metro operates over 2,700 trips daily, starting at around 05:00 and ending at 23:30.