Glyph
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Template:Expert Image:Astrological Glyphs.jpg A glyph is a specific symbol representing a semantic or phonetic unit of definitive value in a writing system. "Glyph" is also commonly expressed as "figure" or "character".
In typography "glyph" refers to elements that may be replaced by more specific terms such as grapheme, ideogram (ideographic glyph), diacritic (augmenting glyph), allograph (two glyphs, one meaning). By contrast, "symbol" refers to a glyph-like mark or figure that evokes a meaning but is not ascribed a specific semantic value. In a font, a "glyph" refers to any symbol or character, whether it be a letter, number, punctuation mark or similar. In digital fonts with multiple versions of some characters, each alternate version of the character is known as a glyph.
Use of the term "glyph" originated from the reference to pictographic (representational) images in the form of carvings. The connection between cultural semantics and forms of sculpture (ie: idols), came to apply to carved or painted representational forms typically based on the sculpture.
The term "hieroglyph" (hiero + glyph) refers to the Ancient Egyptian writing system.
Typography
In typography, a glyph is an allograph: a particular graphical representation of a grapheme, or sometimes several graphemes in combination, or only a part of a grapheme. In computing as well as typography, the term character refers to a grapheme or grapheme-like unit of text, as found in natural language writing systems (scripts). A character or grapheme is a unit of text, whereas a glyph is a graphical unit.
For example, the sequence ffi contains three characters, but can be represented by one glyph, the three characters being combined into a single unit known as a ligature. Conversely, some typewriters require the use of multiple glyphs to depict a single character (for example, two hyphens in place of a dash, or an overstruck apostrophe and period in place of an exclamation mark).
Image:Astro signs.gif Most typographic glyphs originate from the characters of a typeface. In a typeface each character typically corresponds to a single glyph, but there are exceptions, such as a font used for a language with a large alphabet or complex writing system, where one character may correspond to several glyphs, or several characters to one glyph.
In graphonomics, the term glyph is used for a non-character, i.e: either a sub-character or multi-character pattern.
Etymology
Augustan English scholars of the early 18th century, imitating French antiquaries, adopted glyph from the Greek word meaning a "carving." But "glyph" first came to widespread European attention with the engravings and lithographs from Frederick Catherwood's drawings of undeciphered glyphs of the Maya civilization in the early 1840s.
Compare the carved and incised "sacred glyphs" hieroglyphs, which have had a longer history in English dating from the first Elizabethan translation of Plutarch, who adopted "hieroglyphic" as a Latin adjective.