What is seat availability in railway reservations?

Seat availability shows how many vacant berths or seats remain on a specific train for a given journey date and class. It tells you whether a particular train has confirmed seats (CNF), is on Reservation Against Cancellation (RAC), or has gone into the waitlist (WL). The number changes in real time as passengers book tickets, cancel reservations, or as the railway releases quota seats at different stations along the route. Checking seat availability before booking helps you decide which train to take and which travel class fits your budget.