2520: Koppa Ϙ/ϙ Nov 6, 2021

The Phoenician abjad, which is the origin of the Greek alphabet, contained certain letters for sounds that in Greek didn't exist. The Phoenician qoph (pronounced [q]) didn't exist in Greek, and since Greek could already use Κ (kappa) the Greek letter koppa (Ϙ, ϙ) was used before back-vowels. This practice was retained in Etruscan and Italic languages for a while, but unlike Q, which also came from this same Phoenician letter, Ϙ in Greek didn't survive, except sometimes for numerical purposes to represent 90. It is a similar story with the Cyrillic koppa (Ҁ ҁ) which is also now archaic.

2464: C-K-Q were Redundant, Even in Ancient Times Sep 10, 2021

In English C, K, and Q may seem redundant together, but this is not actually new. Etruscan used C before front vowels, K before the vowel [a], and Q before back vowels. Effectively, this would be as if English used two different letters for the T in 'tail' as compared to 'trail', which also changes due to the linguistic environment. These Etruscan letters were therefore not phonemic—the sounds, if theoretically used in each other's places would not have changed the meaning of any word—and were in that sense basically redundant even back then. In Etruscan this may have been phonologically redundant, but there is a very minor, allophonic change that happens going from [ki] to [ka] to [ku] in where the consonant is pronounced in one's mouth. You can try this out yourself.

In Latin, which inherited these letters but did not distinguish between back and front vowels in its spelling, this redundancy was present, and some writers commented on it at the time even. Eventually C morphed into a fricative before E and I, like how it is found in Spanish or Italian today. This therefore made the letter K relevant to distinguish when one wanted to indicate the [k] sound in any context, but still it was not terribly useful.