"Don't let anyone tell you differently, the word alphabet comes from the Greek language". Which is indeed true. The word "alphabet" along with thousands of other words from a lot of languages have a Greek root, then again there are probably just as many words of Latin descent in the world but you don't hear the people from Latin countries claiming words origins from other languages. I wonder why that is... Oh yeah, I remembered, because Greeks are special :)
Every time someone brings up the Greek origin of a word, which you will witness very often if you live in Greece, I remember the "kimono" scene from "My Big Fat Greek Wedding".
Now, before starting to learn Greek there are two very important things you need to remember:
1. Frustration is your friend and
2. Don't try to find a logic. The more you struggle to find a logic the more frustrated you'll get - case in which you need to apply Rule No. 1. I'm not saying that there is no logic, I'm just giving you a friendly advice to not look for it since even if it exists you will not get to it.
The alphabet consists of 24 characters and you think to yourself "How bad can it be". Well, that's your first mistake.
If you crossed paths with math and/or physics at any time in your life, some of the characters will already be known to you. For example "μ" you might remember as being the "coefficient of friction", "η" the energy conversion efficiency in physics or "Δ" the discriminant of the quadratic equation in math.
Out of the 24 characters, 3 are "i"s - there are 5 types of "i"s in Greek but the other two are diphthongs - and two kinds of "o"s. There are no B, D, U, G or J in the alphabet. They exist as sounds but they are compound. For example D as a sound is written "NT" and B is "MP".
A letter that really drove me nuts is "Y". It doesn't make sense right? How can a letter drive you nuts? Well let me tell you. This nice letter may be read: "i", "f", "v" or "u" according to the letters around it.
Dizzy yet?I haven't even got to the good part, the 5 "i"s.
So, the 5 "i"s are: "Ι,ι"; "Η,η"; "Υ,υ"; "οι"; "ει". For the first three I put the smaller and upper cases while the last two are diphthongs. I must admit I have no idea when I should use one kind of "i" and when use another and I don't think I ever will. The rules of use are buried deep in the ancient Greek language which I will never adventure to start learning. That is actually what happens with most of the rules from the modern Greek language. The language is used today but it's grammar rules are stuck way back in the ancient language.
Even though I may never write correctly in Greek that's not that bad after all since not even all Greeks know. While they are very proud of their language, its deep historical roots and its complexity, if you are going to ask five Greeks how to write a word that contains 2-3 "i"s you are most defensively going to have five different opinions and keep in mind that the study of Greek language in schools (ancient and modern) lasts for 6 years.