A slightly more common meaning is a legitimate activity similar to "jury-rig" and just means that you are reappropriating something to do that which it was not necessarily designed to do. A notable example is the LifeHacker blog. Within programming, this type of hacking is generally considered poor practice and again there is no real way to give a three-step process to learn it.
The most common meaning, which this question seems to refer to, involves discovering vulnerabilities in computer software. Within the hacker community there are two main "camps" of hackers, named after a convention of old-west films: black-hat (outlaw) and white-hat (lawman). Black-hat hackers are malicious programmers who exploit vulnerabilities for their own financial gain or amusement, while white-hat hackers disclose them to the appropriate software vendors so they may be patched. Black-hat hackers are also known as crackers, but the general public simply calls them hackers.
Black-hat hacking, or cracking, is an illegal act and can get you into some serious trouble - not only with the law but with viruses attached to supposed cracking tools and resources which will crack your computer and data. White-hat hacking, while not illegal, is essentially the same skill and should not be taught to just any random person who wishes to learn it.
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there are 4 The four games are titled .hack//Infection, .hack//Mutation, .hack//Outbreak, and .hack//Quarantine.
The Tagalog translation for "hack" is "mang-hack" or "humack".
no hack in multiplayer in campaign only have hack monney hack thats hack in campaign
The best hack on Yoville is the money hack.
.hack//SIGN .hack//LIMINALITY (four PSP .hack// games released with an episode) .hack//DUSK
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You can't hack it
you shouldn't hack