Everywhere we go we always encounter display signs in a public facility especially when you are in a building, airplane or boat, this device is what we commonly called an Exit Sign.
I just knew that most exit signs around the world are in pictogram form, with or without text supplement. I know that there has been a shift towards the adoption of such exit signs in the recent decade. I have read that a small minority of nations adhered to the exit signs that show the word "EXIT" (or similar in another language). Its purpose is guiding people to the closest exit in case of fire or other emergency. The English word "exit" comes directly from the Latin word meaning "(he or she) goes out." Most fire codes require exit signs to be permanently lit.
That is so true, here in our country there is a Presedential Decree # 1185 telling us that we really have to lit EXIT SIGNS in order to effect a meaningful reduction of the alarming fire losses, there is a need to develop national consciousness and involvement of all persons in the prevention and suppression of fires.
Since visibility may be reduced in a fire, due to smoke or failure of electric lighting, the sign is often permanently illuminated, usually by one of: (I got it from the Wikipedia)
• Radioluminescence, , self-luminous, where a phosphor coating inside a glass tube glows due to the beta decay of radioactive tritium in the tube.
• Phosphorescence ('glow in the dark'), Photoluminescent, where light is absorbed from the surroundings and slowly re-emitted.
• Electric light, with a local rechargeable power source.
• Electric light, with the building's emergency lighting circuits providing back-up power from a UPS and/or a generator in case normal power is lost.
I guess that’s how important exit signs to us, it's for our own safety!