On a journey of more than 500 km a passenger may break the journey at an intermediate station once for every 500 km, for up to two days, not counting the days of arrival and departure, provided the ticket is endorsed by the station master at the break. The rule exists for point-to-point tickets; it does not apply on Rajdhani, Shatabdi, Duronto and similar trains, or within the first 500 km.
Reserved e-tickets are in practice booked for one train and one berth, so a break journey means giving up the reservation for the onward leg and travelling in the unreserved coach or booking again. The rule matters most for the fare, which stays that of the single through journey.
Also written or searched as: break journey rules · stopover · break of journey