Full writing systems may be defined as collections of arbitrary signs that can represent all the words of the language to which they are applied. Limited writing systems consisting of marks made for counting or identification go back three thousand years. The evolution of full writing systems has taken place only during the past five thousand years.
Writing systems have made possible the technological advances that has taken humanity from hunting, gathering, and simple farming to exploration of space. Writing created a permanent record of knowledge so that a fund of information could accumulate from one generation to the next. Before writing, human knowledge was confined by the limits of memory. For example, learning something from one self or from talking to another.
Early visual systems such as signaling by gestures or with fire or smoke were limited to the range of eyesight and subject to misinterpretation. Writing allowed accurate communication at a distance without traveling or relying on the memory of a messenger.
Writing includes both picture writing, also know as pictography and ideographs. The use of pictures to represent, not the object drawn but some attribute or idea suggested by the object. For example, a drawing of the sun gives you an idea of warmth. Limited writing refers directly to the object or idea portrayed. Pictograms or ideograms call to mind an image or concept that then may be expressed in language. The reader does not need to know the language of the writer to translate the signs into his or her own language.
A full or true writing system represents words not objects. However, the earliest writing systems came from Mesopotamia, Egypt and, Central America. These writing systems only qualify as limited writing since they used signs that refer to the objects represented and not to the words for the object.
International traffic signs are effective because they avoid language. Simple pictures instead of words or phrases, makes it more comprehensible to illiterates and speakers of other languages. They warn drivers of road hazards and traffic regulations, which need to be followed in order to keep the road safe. A few other methods of systems are musical and scientific notation.
Specific technical information like word syllabic and alphabetic writing is used to represent a language. A full writing system must maintain fixed correspondences between its signs and the element of the language.