One who is skilled in the art of h4xlng(hacking). A real hacker does not commit malicious acts. One who does that is known as a cracker(this is not a lie) or a black hat h4x0rz.
Whats wrong with my computer! I need to call some h4x0rz!
One who uses their computer skills to comit molicious crimes against others. Some are skilled computer programmers and specialists. Others are young children, teens, or inexperianced individuals that do these acts for fun or for the rush of acting as a professianal for the first time. Because of the media, the public often thinks of hackers as criminals even though this is not true. Hackers just have a passion for computers and specializing in them.
That cracker just stole and deleted all of my files!