Conversation so far:
what is the meaning of rac in indian railway
A Reservation Against Cancellation (RAC) is a type of ticket that can be sold for travel on the Indian Railways.
what else can you tell me about Reservations against Cancellations
Although it ensures certainty of travel, it does not guarantee a berth.
how does a RAC ticket holder get a berth
A RAC ticket holder is given an empty berth: If there are any last minute cancellations or if any quota remains unsold.

Question: what is a berth
Self-contained rewrite: what is a berth on a train