η without accent is the article

ή with the accent is the disjunctive one... this translates as "or".

Examples

Η Μαρία και η Μαργαρίτα. = Mary and Margaret.

Η Μαρία ή η Μαργαρίτα; = Mary or Margaret?

As you published this in "theeta" discussion, please make sure that you don't confuse "eeta" (η) with "theeta" (θ).

Now theta is also accepted. This is the Erasmian system that wants to attribute the classic Attic phonetical system.

Yes it is.

I don't think they will ever do. Pronunciation would probably be the same as modern Greek considering that no valid ancient pronunciation arrived in our days (i.e. no recordings are available). Phonetic studies and books are also available in the last 300 years so in my opinion shouldn't be considered valid for a language continuously spoken and evolved 2000+ years before. About the grammar there are many books that you can find and study.

Hello! Please read the Tips and notes that are available on the website, just scroll under the lessons. You can also find information on how to add a Greek keyboard here and here. Basically, you need to activate the Greek keyboard by accessing your computer or mobile device language input settings.

Tú habías pensado que era zeta, no theta, ya que estás tratando de traducir tus clases de griego al inglés donde zeta ζ se pronuncia theeta aunque la pronunciación real en griego se acerca más a la pronunciación española. Pd. Soy mexicano, pero lo comprendí perfectamente.