An orthography is a standardized system for using a particular writing system (script) to write a particular language. It includes rules of spelling. Other elements of written language that are part of orthography include hyphenation, capitalization, word breaks, emphasis, and punctuation.
Most significant languages in the modern era are written down, and for most such languages a standard orthography has developed, often based on a standard variety of the language, and thus exhibiting less dialect variation than the spoken language. Sometimes there may be variation in a language's orthography, as between American and British spelling in the case of English. If a language uses multiple writing systems, it may have distinct orthographies, as is the case with Kurdish, Uyghur, Serbian, Inuktitut and Turkish. In some cases orthography is regulated by bodies such as language academies, although for many languages (including English) there are no such authorities, and orthography develops through less formal processes.
Etymology and meaning 
The English word orthography dates from the 15th century. It comes from the French orthographie, from Latin orthographia, which derives from Greek ὀρθός orthós, "correct", and γράφειν gráphein, "to write".
Orthography is largely concerned with matters of spelling, and in particular the relationship between phonemes and graphemes in a language. Other elements that may be considered part of orthography include hyphenation, capitalization, word breaks, emphasis, and punctuation. Orthography thus describes or defines the set of symbols used in writing a language, and the rules about how to use those symbols.
Most natural languages developed as oral languages, and writing systems have usually been crafted or adapted as ways of representing the spoken language. The rules for doing this tend to become standardized for a given language, leading to the development of an orthography that is generally considered "correct". In linguistics the term orthography is often used to refer to any method of writing a language, without judgment as to right and wrong, with a scientific understanding that orthographic standardization exists on a spectrum of strength of convention. The original sense of the word, though, implies a dichotomy of correct and incorrect, and the word is still most often used to refer specifically to a thoroughly standardized, prescriptively correct, way of writing a language. A distinction may be made here between etic and emic viewpoints: the purely descriptive (etic) approach, which simply considers any system that is actually used—and the emic view, which takes account of language users' perceptions of correctness, which are analogous in some ways to a moral sense of right and wrong.
Units and notation 
Orthographic units, such as letters of an alphabet, are technically called graphemes. These are a type of abstraction, analogous to the phonemes of spoken languages; different physical forms of written symbols are considered to represent the same grapheme if the differences between them are not significant for meaning. For example, different forms of the letter "b" are all considered to represent a single grapheme in the orthography of, say, English.
Graphemes or sequences of them are sometimes placed between angle brackets, as in ‹b› or ‹back›. This distinguishes them from phonemic transcription, which is placed between slashes (/b/, /bæk/), and from phonetic transcription, which is placed between square brackets ([b], [bæk]).
The writing systems on which orthographies are based can be divided into a number of types, depending on what type of unit each symbol serves to represent. The principal types are logographic (with symbols representing words or morphemes), syllabic (with symbols representing syllables), and alphabetic (with symbols roughly representing phonemes). Many writing systems combine features of more than one of these types, and a number of detailed classifications have been proposed. For a full discussion, see Writing system: Functional classification of writing systems.
Correspondence with pronunciation 
Orthographies that use alphabets and syllabaries are based on the principle that the written symbols (graphemes) correspond to units of sound of the spoken language: phonemes in the former case, and syllables in the latter. However, in virtually all cases, this correspondence is not exact. Different languages' orthographies offer different degrees of correspondence between spelling and pronunciation. English orthography, for example, is highly irregular, whereas the orthographies of languages such as Russian, Spanish and Finnish represent pronunciation much more faithfully, although the correspondence between letters and phonemes is still not exact. Serbian orthography is remarkably consistent: approximation of the principle "one letter per sound".
An orthography in which the correspondences between spelling and pronunciation are highly complex or inconsistent is called a deep orthography (or less formally, the language is said to have irregular spelling). An orthography with relatively simple and consistent correspondences is called shallow (and the language has regular spelling).
One of the main reasons for which spelling and pronunciation deviate is that sound changes taking place in the spoken language are not always reflected in the orthography, and hence spellings correspond to historical rather than present-day pronunciation. One consequence of this is that many spellings come to reflect a word's morphophonemic structure rather than its purely phonemic structure (for example, the English regular past tense morpheme is consistently spelled -ed in spite of its different pronunciations in various words). This is discussed further at Phonemic orthography: Morphophonemic features.
The syllabary systems of Japanese (hiragana and katakana) are examples of almost perfectly shallow orthographies – the kana correspond with almost perfect consistency to the spoken syllables, although with a few exceptions where symbols reflect historical or morphophonemic features: notably the use of ぢ ji and づ zu (rather than じ ji and ず zu, their pronunciation in standard Tokyo dialect) when the character is a voicing of an underlying ち or つ (see rendaku), and the use of は, を, and へ to represent the sounds わ, お, and え, as relics of historical kana usage.
The Korean hangul system was also originally an extremely shallow orthography, but as a representation of the modern language it frequently also reflects morphophonemic features.
For full discussion of degrees of correspondence between spelling and pronunciation in alphabetic orthographies, including reasons why such correspondence may break down, see Phonemic orthography.
Defective orthographies 
In some cases an orthography based on the principle that symbols correspond to phonemes may lack characters to represent all the phonemes or all the phonemic distinctions in the language. This is called a defective orthography. An example in English is that the digraph th is required to represent two different phonemes (as in either and ether). A more systematic example is that of abjads like the Arabic and Hebrew alphabets, in which the short vowels are normally left unwritten and must be inferred by the reader.
When an alphabet is borrowed to represent a language other than it did originally—as has been done with the Latin alphabet for many languages, or Japanese Katakana for non-Japanese words—it often proves defective in representing the new language's phonemes. Sometimes this problem is addressed by the use of such devices as digraphs (such as sh and ch in English, where pairs of letters represent single sounds), diacritics (like the caron on the letters š and č, which represent those same sounds in Czech), or the addition of completely new symbols (as some languages have introduced the letter w to the Latin alphabet).
See also 
- orthography, Online Etymology Dictionary
- Seidenberg, Mark S. 1992. "Beyond Orthographic Depth in Reading: Equitable Division of Labor." In: Ram Frost & Leonard Katz (eds.). Orthography, Phonology, Morphology, and Meaning, pp. 85–118. Amsterdam: Elsevier, p. 93.
- Donohue, Mark. 2007. "Lexicography for Your Friends." In Terry Crowley, Jeff Siegel, & Diana Eades (eds.). Language Description, History and Development: Linguistic Indulgence in Memory of Terry Crowley. pp. 395–406. Amsterdam: Benjamins, p. 396.
- Coulmas, Florian. 1996. The Blackwell Encyclopedia of Writing Systems. Oxford: Blackwell, p. 379.
- Smalley, W.A. (ed.) 1964. Orthography studies: articles on new writing systems (United Bible Society, London).
- Venezky, Von Richard L.; Tom Trabasso, John P. Sabatini, Dominic W. Massaro, Robert Calfee (2005). From Orthography to Pedagogy. Routledge. ISBN 0-8058-5089-9, 9780805850895 Check
- Videos: The History and Impact of Writing in the West
- Omniglot – writing systems & languages of the world – a privately run orthography website
- Phonemic awareness page of the CTER wiki
- lonestar.texas.net/~jebbo/learn-as/ orthography of Old English