Indira Gandhi Airport has two active passenger terminals: Terminal 1 and Terminal 3, and Terminal 2 which is home to many of the low cost flights of Terminal 1 due to its refurbishing works.
Terminal 1, is used by low cost carriers such as GoAir, IndiGo and SpiceJet, and is divided in Terminal 1-C, used for domestic arrivals, and Terminal 1-D, used for departures, it can handle 15 million passengers annually. It is nowadays closed due to improvement works and all the flights were transferred to Terminal 2.
Terminal 2, it has been redesigned to temporary host the low cost carriers of Terminal 1. Once Terminal 1 will reopen, it will be demolished to build the new Terminal 4.
Terminal 3 is the newest terminal, it was opened in 2010 and is one of the biggest terminals in the world, being able to handle 40 million passengers per year. Other terminals like T1A, T1B are unused nowadays.
All International flights are operated from T3, Domestic Flights are operated in T1 or T3, depending of the Carrier. Lowcost Carriers (GoAir, IndiGo and SpiceJet) are operated from Terminal 1, while the other carriers are operated from T3. Check below some information you must now of both terminals.