The
Delhi Metro is a mass rapid transit system which serves Delhi and its adjoining satellite cities, such as Ghaziabad, Faridabad, Gurugram, Noida and Bahadurgarh, in the National Capital Region of India. The system consists of
10 colour-coded lines serving 256 stations, with a total length of 350.42 kilometres (217.74 mi). It is India's largest and busiest metro rail system and the second-oldest, after the Kolkata Metro. The metro has a mix of underground, at-grade, and elevated stations using broad-gauge and standard-gauge tracks. The metro makes over 4,300 trips daily.