K is the eleventh letter of the modern Latin alphabet. Its name in English ( ) is spelled kay.

The letter K comes from the Greek Κ , which was taken from the Semitic kap, the symbol for an open hand."K". The Oxford English Dictionary, 2nd ed., 1989, online 1 This in turn was likely adapted by Semites who had lived in Egypt from the hieroglyph for "hand" representing D in the Egyptian word for hand, d-r-t. The Semites evidently assigned it the sound value /k/ instead, because their word for hand started with that sound.

In the earliest Latin inscriptions, the letters C, K and Q were all used to represent the sounds /k/ and /g/ (which were not differentiated in writing). Of these, Q was used to represent /k/ or /g/ before a rounded vowel, K before /a/, and C elsewhere. 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".

When Greek words were taken into Latin, the Kappa was converted to C, with a few exceptions such as the praenomen Kaeso. Some words from other alphabets were also transliterated into C. Therefore, the Romance languages have K only in words from still other language groups. The Celtic languages also chose C over K, and this influence carried over into Old English. Today, English is the only Germanic language to productively use hard C in addition to K (although Dutch uses it in learned words of Latin origin and follows the same "hard / soft" distinction in such words as does French and English – but not in native words).

Some English linguists prefer to reverse the Latin transliteration process for proper names in Greek, spelling Hecate as "Hekate", for example. And the writing down of languages that don't have their own alphabet with the Latin one has resulted in a standardization of the letter for this sound, as in Kwakiutl.

In the International Phonetic Alphabet, 2 is the symbol for the voiceless velar plosive.

Several other alphabets also use characters with sharp angles to indicate the sound /k/ or syllables that start with a /k/, for example: Arabic ك, Hebrew כ (in some fonts), Korean ㄱ. This kind of phonetic-visual association was studied by Wolfgang Köhler. However, there are also many examples of rounded letters for /k/, like ค in Thai, Ք in Armenian and C in Latin.

Codes for computing

In Unicode the capital K is codepoint U+004B and the lower case k is U+006B.

The ASCII code for capital K is 75 and for lowercase k is 107; or in binary 01001011 and 01101011, correspondingly.

The EBCDIC code for capital K is 210, and for lowercase k, 146.