Later use

When the Roman alphabet was introduced into Britain, ⟨c⟩ represented only /k/, and this value of the letter has been retained in loanwords to all the insular Celtic languages: in Welsh,^[4] Irish, and Gaelic, ⟨c⟩ represents only /k/. The Old English Latin-based writing system was learned from the Celts, apparently of Ireland; hence ⟨c⟩ in Old English also originally represented /k/; the Modern English words kin, break, broken, thick, and seek all come from Old English words written with ⟨c⟩: cyn, brecan, brocen, þicc, and séoc. However, during the course of the Old English period, /k/ before front vowels (/e/ and /i/) was palatalized, having changed by the tenth century to [tʃ], though ⟨c⟩ was still used, as in cir(i)ce, wrecc(e)a. On the continent, meanwhile, a similar phonetic change before the same two vowels had also been going on in almost all modern romance languages (for example, in Italian).

In Vulgar Latin, /k/ became palatalized to [tʃ] in Italy and Dalmatia; in France and the Iberian peninsula, it became [ts]. Yet for these new sounds ⟨c⟩ was still used before the letters ⟨e⟩ and ⟨i⟩. The letter thus represented two distinct values. Subsequently, the Latin phoneme /k^w/ (spelled ⟨qv⟩) de-labialized to /k/ meaning that the various Romance languages had /k/ before front vowels. In addition, Norman used the letter ⟨k⟩ so that the sound /k/ could be represented by either ⟨k⟩ or ⟨c⟩, the latter of which could represent either /k/ or /ts/ depending on whether it preceded a front vowel letter or not. The convention of using both ⟨c⟩ and ⟨k⟩ was applied to the writing of English after the Norman Conquest, causing a considerable re-spelling of the Old English words. Thus while Old English candel, clif, corn, crop, cú, remained unchanged, Cent, cǣᵹ (cēᵹ), cyng, brece, sēoce, were now (without any change of sound) spelled Kent, keȝ, kyng, breke, and seoke; even cniht ('knight') was subsequently changed to kniht and þic ('thick') changed to thik or thikk. The Old English ⟨cw⟩ was also at length displaced by the French ⟨qu⟩ so that the Old English cwēn ('queen') and cwic ('quick') became Middle English quen and quik, respectively. The sound [tʃ], to which Old English palatalized /k/ had advanced, also occurred in French, chiefly from Latin /k/ before ⟨a⟩. In French it was represented by the digraph ⟨ch⟩, as in champ (from Latin camp-um) and this spelling was introduced into English: the Hatton Gospels, written c. 1160, have in Matt. i-iii, child, chyld, riche, mychel, for the cild, rice, mycel, of the Old English version whence they were copied. In these cases, the Old English ⟨c⟩ gave way to ⟨k⟩, ⟨qu⟩ and ⟨ch⟩; on the other hand, ⟨c⟩ in its new value of /ts/ appeared largely in French words like processiun, emperice and grace, and was also substituted for ⟨ts⟩ in a few Old English words, as miltse, bletsien, in early Middle English milce, blecien. By the end of the thirteenth century both in France and England, this sound /ts/ de-affricated to /s/; and from that time ⟨c⟩ has represented /s/ before front vowels either for etymological reasons, as in lance, cent, or to avoid the ambiguity due to the "etymological" use of ⟨s⟩ for /z/, as in ace, mice, once, pence, defence.

Thus, to show etymology, English spelling has advise, devise (instead of *advize, *devize), while advice, device, dice, ice, mice, twice, etc., do not reflect etymology; example has extended this to hence, pence, defence, etc., where there is no etymological reason for using ⟨c⟩. Former generations also wrote sence for sense. Hence, today the Romance languages and English have a common feature inherited from Vulgar Latin spelling conventions where ⟨c⟩ takes on either a "hard" or "soft" value depending on the following letter.

English

In English orthography, ⟨c⟩ generally represents the "soft" value of /s/ before the letters ⟨e⟩ (including the Latin-derived digraphs ⟨ae⟩ and ⟨oe⟩, or the corresponding ligatures ⟨æ⟩ and ⟨œ⟩), ⟨i⟩, and ⟨y⟩, and a "hard" value of /k/ before any other letters or at the end of a word. However, there are a number of exceptions in English: "soccer" and "Celt" are words that have /k/ where /s/ would be expected.

The "soft" ⟨c⟩ may represent the /ʃ/ sound in the digraph ⟨ci⟩ when this precedes a vowel, as in the words 'delicious' and 'appreciate', and also in the word "ocean" and its derivatives.

The digraph ⟨ch⟩ most commonly represents /tʃ/, but can also represent /k/ (mainly in words of Greek origin) or /ʃ/ (mainly in words of French origin). For some dialects of English, it may also represent /x/ in words like loch, while other speakers pronounce the final sound as /k/. The trigraph ⟨tch⟩ always represents /tʃ/.

The digraph ⟨ck⟩ is often used to represent the sound /k/ after short vowels, like "wicket".

C is the twelfth most frequently used letter in the English language (after E, T, A, O, I, N, S, H, R, D, and L), with a frequency of about 2.8% in words.

Other languages

In the Romance languages French, Spanish, Italian, Romanian and Portuguese, ⟨c⟩ generally has a "hard" value of /k/ and a "soft" value whose pronunciation varies by language. In French, Portuguese, Catalan and Spanish from Latin America and some places in Spain, the soft ⟨c⟩ value is /s/ as it is in English. In the Spanish spoken in most of Spain, the soft ⟨c⟩ is a voiceless dental fricative /θ/. In Italian and Romanian, the soft ⟨c⟩ is [t͡ʃ].

Germanic languages usually use ⟨c⟩ for Romance loans or digraphs, such as ⟨ch⟩ and ⟨ck⟩, but the rules vary across languages. Of all the Germanic languages, only English uses initial ⟨c⟩ in native Germanic words like come. Other than English, Dutch uses ⟨c⟩ the most, for most Romance loans and the digraph ⟨ch⟩. German uses ⟨c⟩ in the digraphs ⟨ch⟩ and ⟨ck⟩, and the trigraph ⟨sch⟩, but by itself only in unassimilated loanwords and proper names. Danish keeps soft ⟨c⟩ in Romance words but changes hard ⟨c⟩ to ⟨k⟩. Swedish has the same rules for soft and hard ⟨c⟩ as Danish, and also uses ⟨c⟩ in the digraph ⟨ck⟩ and the very common word och, "and". Norwegian, Afrikaans, and Icelandic are the most restrictive, replacing all cases of ⟨c⟩ with ⟨k⟩ or ⟨s⟩, and reserving ⟨c⟩ for unassimilated loanwords and names.

All Balto-Slavic languages that use the Latin alphabet, as well as Albanian, Hungarian, Pashto, several Sami languages, Esperanto, Ido, Interlingua, and Americanist phonetic notation (and those aboriginal languages of North America whose practical orthography derives from it) use ⟨c⟩ to represent /t͡s/, the voiceless alveolar or voiceless dental sibilant affricate. In Hanyu Pinyin, the standard romanization of Mandarin Chinese, the letter represents an aspirated version of this sound, /t͡s^h/.

Among non-European languages that have adopted the Latin alphabet, ⟨c⟩ represents a variety of sounds. Yup'ik, Indonesian, Malay, and a number of African languages such as Hausa, Fula, and Manding share the soft Italian value of /t͡ʃ/. In Azeri, Crimean Tatar, Kurmanji Kurdish, and Turkish ⟨c⟩ stands for the voiced counterpart of this sound, the voiced postalveolar affricate /d͡ʒ/. In Yabem and similar languages, such as Bukawa, ⟨c⟩ stands for a glottal stop /ʔ/. Xhosa and Zulu use this letter to represent the click /ǀ/. In some other African languages, such as Berber languages, ⟨c⟩ is used for /ʃ/. In Fijian, ⟨c⟩ stands for a voiced dental fricative /ð/, while in Somali it has the value of /ʕ/.

The letter ⟨c⟩ is also used as a transliteration of Cyrillic ⟨ц⟩ in the Latin forms of Serbian, Macedonian, and sometimes Ukrainian, along with the digraph ⟨ts⟩.

Other systems

As a phonetic symbol, lowercase ⟨c⟩ is the International Phonetic Alphabet (IPA) and X-SAMPA symbol for the voiceless palatal plosive, and capital ⟨C⟩ is the X-SAMPA symbol for the voiceless palatal fricative.

Digraphs

There are several common digraphs with ⟨c⟩, the most common being ⟨ch⟩, which in some languages (such as German) is far more common than ⟨c⟩ alone. ⟨ch⟩ takes various values in other languages.

As in English, ⟨ck⟩, with the value /k/, is often used after short vowels in other Germanic languages such as German and Swedish (other Germanic languages, such as Dutch and Norwegian, use ⟨kk⟩ instead). The digraph ⟨cz⟩ is found in Polish and ⟨cs⟩ in Hungarian, representing /t͡ʂ/ and /t͡ʃ/ respectively. The digraph ⟨sc⟩ represents /ʃ/ in Old English, Italian, and a few languages related to Italian (where this only happens before front vowels, while otherwise it represents /sk/). The trigraph ⟨sch⟩ represents /ʃ/ in German.

Ancestors, descendants and siblings

• 𐤂 : Semitic letter Gimel, from which the following symbols originally derive
  • Γ γ : Greek letter Gamma, from which C derives
    • G g : Latin letter G, which is derived from Latin C
      • Ȝ ȝ : Latin letter Ȝ, which is derived from Latin G
• Phonetic alphabet symbols related to C:
  • ɕ : Small c with curl
  • ʗ : Stretched c
  • 𝼏 : Stretched c with curl - Used by Douglas Beach for a nasal click in his phonetic description of Khoekhoe^[5]
  • 𝼝 : Small letter c with retroflex hook - Para-IPA version of the IPA retroflex tʂ^[6]
  • ꟲ : Modifier letter capital c - Used to mark tone for the Chatino orthography in Oaxaca, Mexico; Used as a generic transcription for a falling tone; Used in para-IPA notation^[7]
• ᶜ : Modifier letter small c^[8]
• ᶝ : Modifier letter small c with curl^[8]
• ᴄ : Small capital c is used in the Uralic Phonetic Alphabet.^[9]
• Ꞔ ꞔ : C with palatal hook, used for writing Mandarin Chinese using the early draft version of pinyin romanization during the mid-1950s^[10]

Add to C with diacritics

• C with diacritics: Ć ć Ĉ ĉ Č č Ċ ċ Ḉ ḉ Ƈ ƈ C̈ c̈ Ȼ ȼ Ç ç Ꞔ ꞔ Ꞓ ꞓ
• Ↄ ↄ : Claudian letters^[11]

Derived ligatures, abbreviations, signs and symbols

• © : copyright symbol
• ℃ : degree Celsius
• ¢ : cent
• ₡ : colón (currency)
• ₢ : Brazilian cruzeiro (currency)
• ₵ : Ghana cedi (currency)
• ₠ : European Currency Unit CE
• ${\displaystyle \mathbb {C} }$ : blackboard bold C, denoting the complex numbers
• ℭ : blackletter C
• Ꜿ ꜿ : Medieval abbreviation for Latin syllables con- and com-, Portuguese -us and -os^[12]

Computing

The Latin letters ⟨C⟩ and ⟨c⟩ have Unicode encodings U+0043 C LATIN CAPITAL LETTER C and U+0063 c LATIN SMALL LETTER C. These are the same code points as were used in ASCII and ISO 8859. There are also precomposed character encodings for ⟨C⟩ and ⟨c⟩ with diacritics, for most of those listed above; the remainder are produced using combining diacritics.

Variant forms of the letter have unique code points for specialist use: the alphanumeric symbols set in mathematics and science, voiceless palatal sounds in linguistics, and halfwidth and fullwidth forms for legacy CJK font compatibility. The Cyrillic homoglyph of the Latin ⟨C⟩ has a separate encoding: U+0421 С CYRILLIC CAPITAL LETTER ES.

Other