Ex-servicemen get a reservation quota in central government Group C and D posts, and many states offer a similar quota.
The exact percentage varies by department and post, so check the reservation section of the official notification.
Age relaxation is also given to ex-servicemen as per government rules.
You need a valid discharge certificate to claim the quota at document verification.
Dependents of ex-servicemen killed in action get separate concessions in some recruitments.
Always read the latest notification, since quota rules can change.