system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: how come the Alphabet and Cyrillic share so many letters that are either identical or very similar looking, and are sometimes pronounced the same/similar and sometimes not?
gpt
The *Latin* alphabet and the *Cyrillic* alphabet are both based very heavily on the *Greek* alphabet. 

Which is why "a" (alpha) is the same in all three, and why "gamma" is a г or "rho" (Р) are the same in Cyrillic and Greek.

Historically, Slavs adopted a form of Greek Orthodoxy (one major branch of Christianity), but the Greek alphabet wasn't enough to express all of the sounds in the Slavic language so they had to create new ones at times, which is roughly how the Cyrillic alphabet came to be.