Quoting Johnk:

when i am asking someone where they are from do i use musunuz or misiniz?

turkum musunuz/misiniz? a turkish dictionary and a local turk have given me 2 slightly different spellins. what is the difference?

Quoting erdinc:

The question suffix in Turkish is -mı, -mi, -mu, -mü. In fact there are many i type suffixes in Turkish and all of them have the vowels ı, i, u, ü.

The simple past tense suffix -dı, -di, -du, -dü and the present continuous tense suffix -ıyor, -iyor, -uyor, -üyor are just two other examples to the -i type suffix.

You pick the correct suffix according vowel harmony. Vowel harmony for i type suffixes means that :

a and ı is followed by ı
e and i is followed by i
o and u is followed by u
ö and ü is followed by ü

Examples:

Çay sıcak mı? (last vowel is a and a is followed by -mı )
Yemek güzel mi? (last vowel is e and e is followed by -mi)
Ali Türk mü? (last vowel is ü and ü is followed by -mü)
Türkçe zor mu? (last vowel is o and o is followed by -mu)

The other part to your question includes the personal suffixes. Here are the personal suffixes for different persons in noun sentences:

Singular
ben : -ım, -im, -um, -üm
sen : -sın, -sin, -sun, -sün
o : -
Plural
biz : -ız, -iz, -uz, -üz
siz : -sınız, -siniz, -sunuz, -sünüz
onlar : -lar, -ler, -

As you see the personal suffix is mostly an 'i' type suffix as well. They have the vowels -ı, -i, -u, -ü. Therefore they follow the same vowel harmony.

The third person plural is an 'a' type suffix or you could use no suffix for that person. Vowel harmony for 'a' type suffixes is easier:

Back vowels are followed by a back vowel and front vowels are followed by a front vowel. So a, ı, o, u is followed by 'a' and e, i, ö, ü, is followed by -e. Another example to the a type suffix would be the plural suffix -ler, lar or the locative case for -de, -da.

A noun sentence is the type of sentence you would construct with the verb to be (am, is, are, was, were, have been, has been) in English. Instead in Turkish we construct them with those personal suffixes.

Notice that because the last vowel is ü in Türk, we use personal suffixes according vowel harmony to ü.

Ben Türk'üm.
Sen Türk'sün.
O Türk.
Biz Türk'üz.
Siz Türk'sünüz.
Onlar Türk.

"Siz Türk müsünüz?"

In this sentence we have the question suffix -mü and the personal suffix -sünüz. Because the personal suffix at the end is already telling us which person it is, we can drop the personal pronoun 'siz' from the sentence.

As you might have noticed the personal pronoun (siz) and the personal suffix (-sünüz) are doing exactly the same job. If we had the chance to recreate the language we would drop the personal suffix and make the language much easier. Unfortunately this wasn't the case in the historical development of Turkish language.

Quoting seyit:

Türkçe'yi bu kadar sade ve özet şekilde öğrettiğiniz için teşekkür ederim, erdinç bey.

Quoting caliptrix:

Quoting seyit:

Benim de Türkçeyi öğrenme sürecim devam ediyor caliptrix

Quoting Johnk:

so "kibrisli misiniz" is correct as i is last letter