Hacking benefits?

What is hacking? reverse engineering? altering original design?

I think some of us "hack" in many of our technology lives, not so much as laughing hugging a ball of cash that the ATM threw up but small things like altering the design of technology, installing informal software to override limits in software (unlimited nudges in MSN, removing annoying software designs etc.) some "hacks" are legit and provide personal benefits to mass produced technology.

The more commonly known involves exploiting "hacked" access to systems and taking advantage of this access (providing damage to other people to provide benefits to themselves). But "hacking" forces can help to provide benefits such as creating more jobs in the security sector and creating a need to develop really advanced technology to protect people from "hackers", they can also be used to battle big giant corporations or dig dirt up on governments?? (highly not recommended)