In the earliest Latin inscriptions, the letters C, K and Q were all used to represent the sounds /k/ and /ɡ/ (which were not differentiated in writing).

Later, the use of C and its variant G replaced most usages of K and Q. K survived only in a few fossilized forms, such as Kalendae, "the calends".

[4] After Greek words were taken into Latin, the kappa was transliterated as a C. Loanwords from other alphabets with the sound /k/ were also transliterated with C. Hence, the Romance languages generally use C, in imitating Classical Latin's practice, and have K only in later loanwords from other language groups.

It is silent when it comes before ⟨n⟩ at the start of a stem, e.g.: English is now the only Germanic language to productively use "hard" ⟨c⟩ (outside the digraph ⟨ck⟩) rather than ⟨k⟩ (although Dutch uses it in loan words of Latin origin, and the pronunciation of these words follows the same hard/soft distinction as in English).

The International Phonetic Alphabet uses ⟨k⟩ for the voiceless velar plosive.