I don't know why but here, in iran, everybody use Hungarian notation? Like strName or txtFirstName.
I think its silly and i hate it. is it common everywhere?

Depends on the language C++ yes, C# not so much.

I use it in Application UI so I know what is what:
lblFirstName --> Label First Name
txtFirstName --> Textbox for First Name
This way when I'm in the business logic or model-view I know to use the correct object.

Not even in Hungary

Barely ever here. I do use in_ and out_ prefixes when dealing with C# forms and don't care much for the datatype of the input / only output into labels or something similar.

I always use it. Maybe because I'm Hungarian :D

@skiilaa no surprise xD