To this day, the Romance languages and Irish avoid using the letter* K*. They always use C (or “qu” in certain cases) to spell the /k/ sound. The reason for this is that the ancient Romans decided not to use K in Latin, substituting C instead.
The Romans first adapted their alphabet from the Etruscans, who used a modified Greek alphabet, with K, of course, for the /k/ sound. The Etruscan language did not distinguish between voiced and unvoiced consonants, so the Etruscan gamma could be pronounced /k/. The Romans perpetuated this habit, and modified the gamma by curving it some more until it looked like C. Then they had to add an extra stroke to distinguish the letter for the /g/ sound: G.
Early on, there was a Latin spelling convention to use C before e and i, K before a and o, and Q before u. This three-way division would actually be useful to distinguish the palatal, velar, and postvelar articulations. But since there was no phonemic distinction between them in Latin, the distinction served no purpose. So they took to using C for the /k/ sound in all positions, except when Qu was followed by a vowel.
The letter K still did not die out; they kept using it for one word, and one word only: Kalendae, the name for the first day of each month.
I wonder why???