Merhaba all

I am rather confused about the meaning and use of "bay" and "bey". As i understood they both mean Mr. or gentlman one is used before the name and the other is after. But how and when are they used and which one is most suitable for which occation?

Any help please in this matter?

Thanks a lot in advance 

This might help a little http://www.turkishlanguage.co.uk/modesofaddress.htm but it doesn´t really explain it fully.

 thanks a lot sonunda it helped

Here is the easiest explanation: 

Don´t use bay when addressing to someone

Actually I have never heard anyone using it

but the rule is, for someone who is called Ali Öztürk, you could say Ali bey or Bay Öztürk. But as I have just said, I have never heard someone saying something like Bay Öztürk. We prefer to address people with their first names.

except that you say "bayanlar baylar!" (ladies and gentlemen!) (not bayanlar beyler)

or "welcome gentlemen" (hoşgeldiniz baylar/beyler)

etc

 There was a cartoon on Jetix "402´ nolu Sınıfın Çocukları"  and all the time the children called the teacher " Bayan Graves " while adressing to her. How can you explain ?

My brother sometimes calls me "Bay <my_name>".

I also sometimes call my friends "Bay <his_name>".

Google gives many hits for "bay Ahmet" for example:

bay ahmet yörük hakkında bilgiler

Diyelim ki Bay Ahmet´in Bay Orhan´dan alacağı, Bay Çetin´e de borcu vardır. O zaman ne yapar Bay Ahmet?

Buradaki 2 CD´den birisinde, Bay Ahmet Özhan söylemekte, ...

... mühendisi olan Bay Ahmet tarafından bir bina inşa edildiğini kabul edelim. ...

So it is used in some ways.

because it is a translation  

so I guess in the original they were saying "Mrs.Graves" and when it is dubbed they should say "Bayan Graves". Graves Hanım wouldn´t work as Graves is the last name. 

And just additional info, in Turkey kids would call their teacher as "öğretmenim" or "hocam".

But as I have said, in real life in Turkey it is really awkward to use it. OK, maybe if you have a Mr. Graves visiting your company, and if he will give a speech, maybe you could say

"Şimdi Bay Graves´i konuşmaya davet ediyorum" (Now I invite Mr. Graves to speak)

But if there is a Turkish person that will give the speech, it is really sounds strange to me to say

"Şimdi Bay Öztürk´ü konuşmaya davet ediyorum"

instead we would say

"Şimdi Ali Bey´i konuşmaya davet ediyorum"

or if you want to be more formal

"Şimdi Sayın (Ali) Öztürk´ü konuşmaya davet ediyorum"

We use "Sayın" instead of Bay more often to address someone with last name.

I did not mean it is never used. I just meant, if you get confused how to use it, just avoid because it is not common to use it anyway.

I said I´ve never heard it, not I´ve never read it

I guess it might be more common in written language.

Traditionally, Turks would use

xxxx bey and xxx hanım for a Turk

and

bay xxxx and bayan xxxxx for a foreigner.

So someone being formal would call me Bayan Marion.

But the distinction is now more blurred and Marion Hanım is also used today.