Now add this info to /faq/post/985
E-Ticket
An e-ticket can be booked up to the time of chart preparation for your train. To book an e-ticket on Internet at Irctc Website you have to enter your ID proof details like PAN Card, Voter’s ID card, Passport, Ration Card, Central/State Govt. ID Card or Driving License. After booking just take a printout of the Electronic Reservation Slip and carry it during travel with the ID proof. For e-tickets while traveling you must carry the electronic reservation slip otherwise you will have to pay...
more...

a fine of Rs. 50. E-tickets can be cancelled only through internet. Cancellation will be confirmed online and the money will be credited to the same back account. E-ticket - The user can take a printout of the Electronic Registration Slip (ERS)
Online ticket Booking Rules
1. For normal I-Ticket, booking is allowed at least two clear calendar days in advance of journey date. 2. For e-Ticket, booking can be done up to chart Preparation approximately 4 to 6 hours before departure of train. For morning trains with departure time up to 12.00 hrs charts are prepared on the previous night. 3. Opening day booking (90th day in advance, excluding the date of journey) will be available only after 8 AM, along with the counters.
I-Ticket and E-Ticket Advantages
1. Online Ticket Purchase cut is not only easy but it saves your money by cutting down the the role of middle men/ brokers/ agents 2. Forget about long queues in a station for booking tickets. Now customer can book tickets sitting peacefully in office or home on Irctc site on the Internet.
*copied from:bit.ly/w03qm5
For smartphone users QR Code also posted: