The letter 'G' was introduced in the Old Latin period as a variant 'c' to distinguish voiced /ɡ/ from voiceless /k/. The recorded originator of 'g' is freedman Spurius Carvilius Ruga, the first Roman to open a fee-paying school, who taught around 230 BC. At this time, 'k' had fallen out of favor, and 'c', which had formerly represented both /ɡ/ and /k/ before open vowels, had come to express /k/ in all environments.
Ruga's positioning of 'g' shows that alphabetic order related to the letters' values as Greek numerals, was a concern even in the 3rd century BC. Sampson (1985) suggests that: "Evidently the order of the alphabet was felt to be such a concrete thing that a new letter could be added in the middle only if a 'space' was created by the dropping of an old letter." According to some records, the original seventh letter, 'z', had been purged from the Latin alphabet somewhat earlier in the 3rd century BC by the Roman censor Appius Claudius, who found it distasteful and foreign.
Eventually, both velar consonants /k/ and /ɡ/ developed palatalized allophones before front vowels; consequently in today's Romance languages, 'c' and 'g' have different sound values depending on context. Because of French influence, English orthography shares this feature.
Typographic forms 
The modern lowercase 'g' has two typographic variants: the single-story (sometimes opentail) '' and the double-story (sometimes looptail) ''. The single-story form derives from the majuscule (uppercase) form by raising the serif that distinguishes it from 'c' to the top of the loop, thus closing the loop, and extending the vertical stroke downward and to the left. The double-story form (g) had developed similarly, except that some ornate forms then extended the tail back to the right, and to the left again, forming a closed bowl or loop. The initial extension to the right was absorbed into the upper closed bowl. The double-story version became popular when printing switched to "Roman type" because the tail was effectively shorter, making it possible to put more lines on a page. In the double-story version, a small top stroke in the upper-right, often terminating in an orb shape, is called an "ear".
Generally, the two forms are complementary, but occasionally the difference has been exploited to provide contrast. The 1949 Principles of the International Phonetic Association recommends using for advanced voiced velar plosives (denoted by Latin small letter script G) and for regular ones where the two are contrasted, but this suggestion was never accepted by phoneticians in general, and today '' is the symbol used in the International Phonetic Alphabet, with '' acknowledged as an acceptable variant, and is more often used in printed materials.
In English, the letter appears either alone or in some digraphs. Alone, it represents
- a voiced velar plosive (/ɡ/ or "hard G"), as in goose, gargoyle and game;
- a voiced palato-alveolar affricate (/dʒ/ or "soft G"), as in giant, ginger and geology or
- a voiced palato-alveolar sibilant (/ʒ/) in some words of French origin, such as rouge, beige and genre.
The digraph 'dg' represents
- a voiced palato-alveolar affricate (/dʒ/) as in bridge or judge.
The digraph 'ng' represents either
- a velar nasal (/ŋ/) as in length and sing, or
- a consonant cluster of the latter with the hard G (/ŋg/) as in jungle and finger.
- /f/ in enough,
- /ɡ/ in loan words like spaghetti
- as an indicator of a letter's "long" pronunciation in words like sigh and night, or
- 'gh' may be silent as in eight and plough.
The digraph 'gn' may represent
- /nj/, also common in loanwords, as in lasagna or
- initially or finally, simply /n/ as in gnome and sign.
In words of Romance origin, 'g' is mainly soft before 'e', 'i', and 'y' and hard otherwise, although it is soft in algae, gaol, margarine, and an alternative pronunciation of vegan. While the soft value of 'g' varies in different Romance languages (/ʒ/ in French and Portuguese, [(d)ʑ] in Catalan, /d͡ʒ/ in Italian and Romanian, and /x/ in some Spanish dialects, and /h/ in other dialects), in all except Romanian and Italian, soft 'g' has the same pronunciation as the 'j'.
In Italian and Romanian, 'gh' is used to represent /ɡ/ before front vowels where 'g' would otherwise represent a soft value. In Italian and French, 'gn' is used to represent the palatal nasal /ɲ/, a sound somewhat similar to the 'ny' in English canyon. In Italian, the trigraph 'gli', when appearing before a vowel, represents the palatal lateral approximant /ʎ/; in the definite article and pronoun gli /ʎi/, the digraph 'gl' represents the same sound.
There are many English words of non-Romance origin where 'g' is hard though followed by 'e' or 'i' (e.g. get, gift), and a few in which 'g' is soft though followed by 'a' (margarine). Non-Romance languages typically use 'g' to represent /ɡ/ regardless of position.
Amongst European languages Dutch is an exception as it does not have /ɡ/ in its native words, and instead 'g' represents a voiced velar fricative /ɣ/, a sound that does not occur in modern English, but there is a dialectal variation - many Netherlandic dialects use a voiceless fricative ([x] or [χ]) instead, and in southern dialects it may be palatalized to [ʝ]. Nevertheless, word-finally it is always voiceless in all dialects, including standard Netherlandic and standard Belgian Dutch. On the other hand, some dialects (like Amelands), may have a phonemic /g/.
Other scripts 
Strictly speaking, the letter 'g' is not present in other scripts, but the sound it represents is present in many world languages, and is represented by many different graphemes.
The Cyrillic script analogue is marked as 'г' (e.g. in Russian, Bulgarian, Macedonian, Serbian, etc.) or 'ґ' (in Ukrainian as additional letter with a slightly different pronunciation). The Hebrew analogue is gimel 'ג'. Devanagari has forms for both aspirated and un-aspirated 'g' sounds. (घ,ग)
Classical Arabic did not have plain /ɡ/ in its native words (the palatalized form /ɡʲ/ or /ɟ/ is believed to have been used), but the sound is standard in Modern Standard Arabic in Egypt, so as [ɡ] is the standard sound in Egyptian Arabic, in which loanwords are normally transcribed with 'ج' (Gīm). However, foreign words containing /ɡ/ may be transcribed using other letters, such as: گ (Gāf, not part of standard letters), ق (qāf), ك (kāf), غ (Ghain) in loanwords or in varieties of Arabic, but not in Egypt, because 'ج' is normally pronounced [ɡ] in all cases.
Related letters and other similar characters 
- Ĝ ĝ : Latin letter G with circumflex
- Ğ ğ : Latin letter G with breve
- Ɣ ɣ : Latin gamma
- Ȝ ȝ : Latin letter Yogh
- Γ γ : Greek letter Gamma
- Г г : Cyrillic letter Ge
- Ѓ ѓ : Cyrillic letter Gje
- Ғ ғ : Cyrillic letter Ghayn
Computing codes 
|Unicode name||LATIN CAPITAL LETTER G||LATIN SMALL LETTER G|
|Numeric character reference||G||G||g||g|
- 1 Also for encodings based on ASCII, including the DOS, Windows, ISO-8859 and Macintosh families of encodings.
Other representations 
See also 
- Media related to G at Wikimedia Commons
- The dictionary definition of G at Wiktionary
- The dictionary definition of g at Wiktionary
- Lewis and Short Latin Dictionary: G
Letter G with diacritics