Signage

Signage is any kind of visual graphics created to display information to a particular audience. This is typically manifested in the form of wayfinding information in places such as streets or inside/outside of buildings.
Function of signage
The main purpose of signage is communication, to convey information such that its receiver can make cognitive decisions based on the information provided. In general, signage can be classified into the following functions:

(1) Information: signs giving information about services and facilities. (maps, directories, instructions for use, etc) 

(2)Direction: signs leading to services, facilities, functional spaces and key areas (sign posts, directional arrows, etc)

(3)Identification: signs indicating services and facilities. (room names & numbers, toilet signs, number of floors, etc)

(4)Safety and Regulatory: signs giving warning or safety instructions. (warning signs, traffic signs, exit signs, rules & regulations, etc)

photo taken from: google image.