1. The belief that information-sharing is a powerful positive good, and that it is an ethical duty of hackers to share their expertise by writing open-source code and facilitating access to information and to computing resources wherever possible.
2. The belief that system-cracking for fun and exploration is ethically OK as long as the cracker commits no theft, vandalism, or breach of confidentiality.
Both of these normative ethical principles are widely, but by no means universally, accepted among hackers. Most hackers subscribe to the hacker ethic in sense 1, and many act on it by writing and giving away open-source software. A few go further and assert that all information should be free and any proprietary control of it is bad; this is the philosophy behind the GNU project.
Sense 2 is more controversial: some people consider the act of cracking itself to be unethical, like breaking and entering. But the belief that ‘ethical’ cracking excludes destruction at least moderates the behavior of people who see themselves as ‘benign’ crackers (see also samurai, gray hat). On this view, it may be one of the highest forms of hackerly courtesy to (a) break into a system, and then (b) explain to the sysop, preferably by email from a superuser account, exactly how it was done and how the hole can be plugged — acting as an unpaid (and unsolicited) tiger team.
The most reliable manifestation of either version of the hacker ethic is that almost all hackers are actively willing to share technical tricks, software, and (where possible) computing resources with other hackers. Huge cooperative networks such as Usenet, FidoNet and the Internet itself can function without central control because of this trait; they both rely on and reinforce a sense of community that may be hackerdom's most valuable intangible asset.