Is hacking illegal?

Yes, it is absolutely illegal. You can get into big trouble and go straight to jail. In the US there are over 20 thousand laws regarding hacking and its kind. As a matter of fact, you are no longer aloud to go onto your computer without first getting permission from the government. That is what our country turned into. Basically, we are fundamentalist, socialist and soon to be communist.
Sometimes it is, other times it isnt.