Writing system

General properties
Writing systems are distinguished from other possible symbolic communication systems in that one must usually understand something of the associated language in order to successfully read and comprehend the text. Contrast this with other possible symbolic systems such as information signs, painting, maps, and mathematics, which do not necessarily depend upon prior knowledge of a given language in order to extract their meaning.

Every human community possesses language, a feature regarded by many as an innate and defining condition of humankind. However, the development and adoption of writing systems has occurred only sporadically. Once established, writing systems are on the whole modified more slowly than their spoken counterparts, and often preserve features and expressions which are no longer current in the discourse of the speech community. The great benefit conferred by writing systems is their ability to maintain a persistent record of information expressed in a language, which can be retrieved independently of the initial act of formulation.

All writing systems require:

* a set of defined base elements or symbols, individually termed characters or graphemes, and collectively called a script;
* a set of rules and conventions understood and shared by a community, which arbitrarily assign meaning to the base elements, their ordering, and relations to one another;
* a language (generally a spoken language) whose constructions are represented and able to be recalled by the interpretation of these elements and rules;
* some physical means of distinctly representing the symbols by application to a permanent or semi-permanent medium, so that they may be interpreted (usually visually, but tactile systems have also been devised).

Basic terminology
The study of writing systems has developed along partially independent lines in the examination of individual scripts, and as such the terminology employed differs somewhat from field to field.

The generic term text may be used to refer to an individual product of a writing system. The act of composing a text may be referred to as writing, and the act of interpreting the text as reading. In the study of writing systems, orthography refers to the method and rules of observed writing structure (literal meaning, "correct writing"), and in particular for alphabetic systems, includes the concept of spelling.

A grapheme is the technical term coined to refer to the specific base or atomic units of a given writing system. Graphemes are the minimally significant elements which taken together comprise the set of "building blocks" out of which texts of a given writing system may be constructed, along with rules of correspondence and use. The concept is similar to that of the phoneme used in the study of spoken languages. For example, in the Latin-based writing system of standard contemporary English, examples of graphemes include the majuscule and minuscule forms of the twenty-six letters of the alphabet (corresponding to various phonemes), marks of punctuation (mostly non-phonemic), and a few other symbols such as those for numerals (logograms for numbers).

Note that an individual grapheme may be represented in a wide variety of ways, where each variation is visually distinct in some regard, but all are interpreted as representing the "same" grapheme. These individual variations are known as allographs of a grapheme (compare with the term allophone used in linguistic study). For example, the minuscule letter a has different allographs when written as a cursive, block, or typed letter. The selection between different allographs may be influenced by the medium used, the writing instrument, the stylistic choice of the writer, and the largely unconscious features of an individual's handwriting.

The terms glyph, sign and character are sometimes used to refer to a grapheme. Common usage varies from discipline to discipline; compare cuneiform sign, Maya glyph, Chinese character. The glyphs of most writing systems are made up of lines (or strokes) and are therefore called linear, but there are glyphs in non-linear writing systems made up of other types of marks, such as Cuneiform and Braille.

Writing systems are conceptual systems, as are the languages to which they refer. Writing systems may be regarded as complete according to the extent to which they are able to represent all that may be expressed in the spoken language.

History of writing systems
Writing systems were preceded by proto-writing, systems of ideographic and/or early mnemonic symbols. The best known examples are:

* Jiahu Script, symbols on tortoise shells in Jiahu, ca. 6600 BC

* Vinca script (Tărtăria tablets), ca. 4500 BC

* Early Indus script, ca. 3500 BC

The invention of the first writing systems is roughly contemporary with the beginning of the Bronze Age in the late Neolithic of the late 4th millennium BC. The Sumerian archaic cuneiform script and the Egyptian hieroglyphs are generally considered the earliest writing systems, both emerging out of their ancestral proto-literate symbol systems from 3400–3200 BC with earliest coherent texts from about 2600 BC.

The Chinese script likely developed independently of the Middle Eastern scripts, around 1600 BC.

The pre-Columbian Mesoamerican writing systems (including among others Olmec and Maya scripts) are also generally believed to have had independent origins.

It is thought that the first true alphabetic writing appeared around 2000 BC, as a representation of language developed by Semitic workers in Egypt (see History of the alphabet). Most other alphabets in the world today either descended from this one innovation, many via the Phoenician alphabet, or were directly inspired by its design.
Types of writing systems
The oldest-known forms of writing were primarily logographic in nature, based on pictographic and ideographic elements. Most writing systems can be broadly divided into three categories: logographic, syllabic and alphabetic (or segmental); however, all three may be found in any given writing system in varying proportions, often making it difficult to categorise a system uniquely. The term complex system is sometimes used to describe those where the admixture makes classification problematic.