IN RAILWAYS, SIGNALS ARE USED AS A MODE OF COMMUNICATION FOR SAFE TRANSPORTATION OF PASSENGERS AND GOODS THROUGH ITS INTRICATE RAILROAD NETWORK LAID OUT AROUND THE WORLD. THIS IS INTERESTINGLY EXPLAINED THROUGH POSTAGE STAMPS, POST MARKS, POSTAL STATIONERY, ETC., THAT TALK ABOUT THE HISTORY, NECESSITY, TYPES AND EVOLUTION OF RAILWAY SIGNALLING SYSTEM.