about read() function

Hello everybody~~
I want to know read() function...
As my think, read() wait until incoming data to COM port..
I know like this...
but if serial buffer is empty, read() returns immediately.
so I programmed the "serial receiving" using pollin...
Please teach me about this problem... read() function....
Really read() doesn't wait serial incoming?
(sorry, My English is very very poor, but I can't input Korean now....)