Kaaf is the eleventh letter of the Samaritan alphabet and carries the numeral value twenty, the second of the tens after yut. It writes a plain k. The name is the inherited Northwest Semitic one behind Hebrew kaf, glossed as the palm of the hand, a reading argued backwards from the word rather than attested.
Kaaf is the third of the single letter prepositions that attach to the front of a word, after bit and labat: it means like or as, and it is the letter that makes a comparison. Suffixed instead of prefixed it marks the second person possessive. Between those two jobs it appears constantly, and in a script with no final forms it appears in the same shape whichever end of the word it is on, which is not true of its Hebrew counterpart.
Greek took the sign as kappa and kept its sound and its position. Latin took kappa from Greek but used it sparingly, preferring C for the k sound, which is why K is an uncommon letter in Latin and in several of the languages that took the Latin alphabet from it. That is a change of fashion in one alphabet rather than a change in the sign, which has written a k in the Semitic scripts without interruption throughout.
The character is encoded at U+080A.