What is a Hacker?
I believe a person is only a hacker if another hacker calls them one. Perhaps a better definition is a person who manipulates a system in ways other than were intended by the system designers and operators. I feel hacking is more than just penetrating systems without permission, but there is definitely an overlap of skills. To illustrate hacking, I am going to recount some stories from my past. If this is not informative, I hope it is at least entertaining.
The first personal computer I ever saw was an Apple ][+ at my future best friend Mike's house. The next Christmas, I got an Apple ][+ and fell in love with it. The first hack I learned was that the 360k 5¼" floppy disks were double-sided, but unmodified would only work with one side up. So we took a hole-punch, flipped a second disk over as a template, and notched the disks so we could write to both sides. Perhaps a more "hackish" trick we learned was that a hex editor could be used to cheat at computer games. In Ultima for example, we could increase our character's strength, hit points, etc. Scrolling through the hex looking for clear text key value pairs taught me how to manipulate trust to get what I wanted - the game writer "trusted" the players not to modify the game to make it easier.
About a year later the movie War Games came out and suddenly all the older kids wanted to be hackers. It was cool to be a phone phreak. That Christmas, I got a modem and started calling BBSes. Shared knowledge amplified intelligence. I also learned how to be cautious and think about what sort of "trail" I might be leaving with my activities. The real phreaks were brute forcing long distance calling codes and 800 numbers. I read that an 800 number call would be traced as a matter of course so that charges could be accurately calculated. This was O.K. if calling from a phone booth, but not a good idea from my parents' second phone line in our home office. I also learned to trade information and, as long as I did not take credit as being the originator, the community was O.K. with me sharing it.
Fifteen years later, the Internet was up and running. I learned to do things like dial into the local library for their card catalog. It used Lynx and I could give it any URL and surf for free. I also learned to use the "find" command in shared hosting accounts to find MP3 and movie files of other users. Like 800 numbers, everyone had an IP address that could be tracked.
Hackers are motivated by fun or the rush of learning something new and forbidden. Hackers are not motivated by greed or scams, but there should be some sort of reward for their activities. Hackers succeed by discovering flaws of unverified trust in a system, like a buffer overflow or SQL injection. As Linus wrote, the highest form is "for the fun of it."