Traffic signs or road signs are signs erected at the side of or above roads to give instructions or provide information to road users. The earliest signs were simple wooden or stone milestones.
A warning sign is a type of sign which indicates a potential hazard, obstacle, or condition requiring special attention. Some are traffic signs that indicate hazards on roads that may not be readily apparent to a driver.[
A symbol is a mark, sign, or word that indicates, signifies, or is understood as representing an idea, object, or relationship. Symbols allow people to go beyond what is known or seen by creating linkages between otherwise very different concepts and experiences. All communication (and data processing) is achieved through the use of symbols. Symbols take the form of words, sounds, gestures, ideas, or visual images and are used to convey other ideas and beliefs. For example, a red octagon is a common symbol for "STOP"; on maps, blue lines often represent rivers; and a red rose often symbolizes love and compassion. Numerals are symbols for numbers; letters of an alphabet may be symbols for certain phonemes; and personal names are symbols representing individuals. The variable 'x', in a mathematical equation, may symbolize the position of a particle in space.
The academic study of symbols is semiotics. In cartography, an organized collection of symbols forms a legend for a map.
Pictorial symbols (also "image", "iconic", or "replicative") appear as the real-world feature, although it is often in a generalized manner; e.g. a tree icon to represent a forest, or green denoting vegetation.
Functional symbols (also "representational") directly represent the activity that takes place at the represented feature; e.g. a picture of a skier to represent a ski resort or a tent to represent a campground.
Conceptual symbols directly represent a concept related to the represented feature; e.g. a dollar sign to represent an ATM, or a Star of David to represent a Jewish synagogue.
Conventional symbols (also "associative") do not have any intuitive relationship but are so commonly used that map readers eventually learn to recognize them; e.g. a red line to represent a highway or a cross to represent a hospital.
Abstract/geometric symbols (also "adhHoc") are arbitrary shapes chosen by the cartographer to represent a certain feature.
