[Originally posted on 03/25/15 on the Duolingo Turkish for English speakers forum by AlexinNotTurkey]
There are no articles in Turkish! The number one (bir) is sometimes used to distinguish between the/a(n). However, if a noun is in the subject position, there is no way to tell! Cool, right? This being said, if the noun is in the object position, Turkish does distinguish between the/a(n). You will learn more about this in the Accusative Case.
Additionally, if there is an adjective preceding the noun, “bir” is no longer optional. For example:
“Mavi kedi” — “The blue cat”
“Mavi bir kedi” — “A blue cat”
[Updated by Danika_Dakika starting 03/01/22]