why we can't create folder with name 'con'?

Hi,

You can't make folders on the desktop that have "System Action" or "Device"  references such
as con, nul and prn. Solution is to use another name or use 0 instead of o,O for C0n.

Here are others :

CON, PRN, AUX, CLOCK$, NUL, COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8, COM9,
LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, LPT9

Can you create “con” folder on windows os ?
http://freetechjournal.com/windows-tips/create-con-folder-windows-xp-os.html

HAPPY CODING