It is common to greet people when they are meet. and ask about how they are.
Merhaba : Hello // Usage of this word is limited. Most of the people use selam.
Selam : Hi
Naber? (Long form is ne haber) : something similar to “What’s up”
Nasılsın? : How are you?
İyiyim : I am fine
Kötüyüm : I am bad.
Lets practice some conversational Turkish
M- Selam Alper.
A- Selam Mehmet naber?
M- İyi ya senden? //Fine What about you?
A- İyi Teşekkür ederim. //Fine thanks
M-Selam Alper.
A-Selam
M-Nasılsın?
A- İyi. sen nasılsın?
M- Ben de iyiyim. // I am fine too.