someone who plays golf poorlya programmer who breaks into computer systems in order to steal or change or destroy information as a form of cyber-terrorisma programmer for whom computing is its own reward; may enjoy the challenge of breaking into other computers but does no harm; "true hackers subscribe to a code of ethics and look down upon crackers"
You may never know you've been hacked if all they seek is information; if they want to do damage ... you'll know!
I just wondered if a person I mentioned on another forum was a hacker, that's why he had so many servers. If someone is on a forum for say 20 mins and there is no activity, could they be hacking or just putting the kettle on.
Do not argue with an idiot. He will drag you down to his level and beat you with experience