What are concessions available for Passengers?

What are the different types of concessions available for Passengers?

At present Indian Railways offers Concession tickets only to Senior Citizens (Age equal or above 60 years for Male & Age equal or above 60 years for Female).
This concession is also offered only on specific request made by the User by clicking the relevant button on the online reservation form.
Other concession tickets can be availed at the PRS counters at any Railway Reservation Office.(Children below 12 years need pay only 50% fare, as for normal tickets) No concession of any type including senior
citizen for tatkal ticket.