Originally posted by: Selcen_Ozturk https://forum.duolingo.com/comment/8070304
In English, when you say "I have a bag", you are talking about possession, you are giving the information that you are the owner of any bag. We translate these sentences into Turkish as "Benim (bir) çantam var", literally "There is my bag" (note: please don't suggest such sentences as alternatives 
). There is also a verb, sahip olmak, so the alternative is"Ben (bir) çantaya sahibim." but it is less common.
When you say "I have the bag", you are certainly not giving any information about possession, this sentence only tells us about the location, that it is you who currently have the bag, maybe it is mine, but I left in your car, with you. Therefore, Turkish uses locative for this. So, "I have the bag" will be translated as "çanta bende". Similarly, "I have your bag" is "çantan bende"
What about possession of a specific object? There are different ways to tell it in English:
- I own the bag. (Çantaya ben sahibim –“ben” is not really optional here/Çanta bana ait)
- I possess the bag. (Çantaya ben sahibim –“ben” is not really optional here/Çanta bana ait)
- The bag is mine. (Çanta benim/Çantaanta benimki)
- The bag belongs to me. (Çanta bana ait)
I hope it is clear for you all. Happy learning!