Looking To Book A Train Ticket? IRCTC Reservation Rules Explained Here

Passengers can book a ticket up to 120 days in advance for all classes and trains. However, in case of some intercity day trains, the ARP (Advance Reservation Period) is less than 60 days.
One must be a registered user to IRCTC's website/app to book tickets and for any type of enquiries. No user can register more than once on the site.
Online booking of train tickets are allowed from 00:20 am to 11:45 pm (Indian Standard Time) on all days including Sundays, according to IRCTC.
All payments towards the cost of the tickets issued should be done through one of the payment mode provided on the payment page, according to IRCTC.
For Tatkal booking, opening day means one day in advance from date of departure of train from originating station. For e.g.-if train is to depart from originating station on August 2, Tatkal booking will commence at 10.00 AM on August 1.
Bookings can be done against General (GN), Senior Citizen (SS), Ladies (LD) and Tatkal (TQ) quota berths/seats only.
Under Tatkal quota, berths/seats are earmarked in all-important trains in different classes except First Class Air-conditioned (1A) class.
Ladies Quota (LD) is generally earmarked in sleeper class (SL) and second sitting (2S).
Auto upgradation is available to the next higher class on optional basis, as per railway rules.
Cancellation of e-tickets can be done by passengers only before chart preparation of the train. After chart preparation, passengers can use the online TDR (ticket deposit receipt) filing facility and track the status of refund.