Difference between -요 and -야?
I know -요 is showing respect, but what is -야? I've things like 뭐요/뭐야 and 바보요/바보야. How do you use -야?

Question

Difference between -요 and -야?
I know -요 is showing respect, but what is -야? I've things like 뭐요/뭐야 and 바보요/바보야. How do you use -야?

Answer

Hehe, they have nothing to do with each other. 야 means "is".

뭐야? / 뭐예요? = what is...?

뭐? / 뭐요? = What?

Answer

the ending 야 is a casual ending so you use it only between friends or those younger than you. Unless you want to be rude :P

Edit. Oh, yeah, I forgot to add that 야 is the casual ending of the verb 이다 (to be) as jon mentions.

Polite form = 이에요
Casual form = 이야