Indian Railways Reservation Against Cancellation(RAC), Wait List(WL), Confirm(CNF) what does these words mean??

WL = Waitlist
RAC = Reservation against cancellation
CNF  = Confirmed Reservation.

An RAC ticket gets you on the train but a  WL ticket doesn’t,

but there’s a chance you could end up with just a seat for RAC

A berth is split into 2 seats for 2 RAC ticket holders, if there are any last minute cancellations then an RAC ticket holder is given the empty berth.

the other RAC ticket holder can then convert the 2 seats into a berth.

RAC tickets are only issued for 

2-tier air condn (4 seats per carriage),

 3-tier air condn (6 seats per carriage), 

on air condn First Class (4 seats per carriage), 

and non air con Sleeper Class (up to 12 seats per carriage).

Lets assume you have reserved a ticket at a WL 10.

Tickets will be sold in the following order....(4 RAC places in this example)

1. Available 02
2. Available 01
3. RAC 01
4. RAC 02
5. RAC 03
6. RAC 04
7. WL 01
8. WL 02

WL 10/WL 4 means that you join the waitlist at position 10, but due to cancellations (before you bought the ticket) you have already moved to waitlist position 4

If there are still another 3 cancellations then your new waiting position would be WL 10/WL 1.

If there are another 3 cancellations  then your status would be WL 10/RAC 2, 

further 2 more cancellations would take you to WL 10/CNF (confirmed reservation).

Note:-

WL 10/WL 4 = is still a waitlisted ticket, you can’t board the train with a waitlisted ticket.

WL 10/RAC 2 = is an RAC ticket, you can board the train with an RAC ticket but you may only get a seat instead of a berth. (more later)

WL 10/CNF = is a confirmed ticket, you can board the train with a confirmed ticket and find your berth.