Throughout history, each writing system invented without prior knowledge of writing gradually evolved from a system of proto-writing that included a small number of ideographs, which were not fully capable of encoding spoken language, and lacked the ability to express a broad range of ideas.
Writing systems are generally classified according to how its symbols, called graphemes, relate to units of language.
Alphabets use graphemes called letters that generally correspond to spoken phonemes, and are typically classified into three categories.
By contrast, logographic (alternatively morphographic) writing systems use graphemes that represent the units of meaning in a language, such as its words or morphemes.
[7] The relationship between writing and language more broadly has been the subject of philosophical analysis as early as Aristotle (384–322 BC).
[12] While researchers of writing systems generally use some of the same core terminology, precise definitions and interpretations can vary by author, often depending on the theoretical approach being employed.
Graphemes are generally defined as minimally significant elements which, when taken together, comprise the set of symbols from which texts may be constructed.
These variant glyphs are known as the allographs of a grapheme: For example, the lowercase letter ⟨a⟩ may be represented by the double-storey |a| and single-storey |ɑ| shapes,[16] or others written in cursive, block, or printed styles.
The choice of a particular allograph may be influenced by the medium used, the writing instrument used, the stylistic choice of the writer, the preceding and succeeding graphemes in the text, the time available for writing, the intended audience, and the largely unconscious features of an individual's handwriting.
For example, English orthography includes uppercase and lowercase forms for 26 letters of the Latin alphabet (with these graphemes corresponding to various phonemes), punctuation marks (mostly non-phonemic), and other symbols, such as numerals.
Proto-writing uses ideographic and mnemonic symbols to communicate, but lacks the capability to fully encode language.
There is no evidence of contact between China and the literate peoples of the Near East, and the Mesopotamian and Chinese approaches for representing aspects of sound and meaning are distinct.
[22][23][24] The Mesoamerican writing systems, including Olmec and the Maya script, were also invented independently.
[25] With each independent invention of writing, the ideographs used in proto-writing were decoupled from the direct representation of ideas, and gradually came to represent words instead.
This allowed words without concrete visualizations to be represented by symbols for the first time; the gradual shift from ideographic symbols to those wholly representing language took place over centuries, and required the conscious analysis of a given language by those attempting to write it.
[31] Depending on the author, the older term logographic ('word writing') is often used, either with the same meaning as morphographic, or specifically in reference to systems where the basic unit being written is the word.
Recent scholarship generally prefers morphographic over logographic, with the latter seen as potentially vague or misleading—in part because systems usually operate on the level of morphemes, not words.
For example, logographs found within phonetic systems like English include the ampersand ⟨&⟩ and the numerals ⟨0⟩, ⟨1⟩, etc.—which correspond to specific words (and, zero, one, etc.)
As each character represents a single unit of meaning, thousands are required to write all the words of a language.
[36] Logograms are sometimes conflated with ideograms, symbols which graphically represent abstract ideas; most linguists now reject this characterization:[37] Chinese characters are often semantic–phonetic compounds, which include a component related to the character's meaning, and a component that gives a hint for its pronunciation.
They were the first alphabets to develop historically,[43] with most used to write Semitic languages, and originally deriving from the Proto-Sinaitic script.
[51] As hangul was consciously created by literate experts, Daniels characterizes it as a "sophisticated grammatogeny"[52]—a writing system intentionally designed for a specific purpose, as opposed to having evolved gradually over time.
[53] In the initial historical distinction, linear writing systems (e.g. the Phoenician alphabet) generally form glyphs as a series of connected lines or strokes.
Egyptian hieroglyphs and Maya script were often painted in linear outline form, but in formal contexts they were carved in bas-relief.
The original system—which Louis Braille (1809–1852) invented in order to allow visually impaired people to read and write—used characters that corresponded to the letters of the Latin alphabet.
[citation needed] Writing systems may be characterized by how text is graphically divided into lines, which are to be read in sequence:[59] For example, English and many other Western languages are written in horizontal rows that begin at the top of a page and end at the bottom, with each row read from left to right.