Hacker ethic term "hack" arose from MIT lingo, as the word had long been used to describe college pranks that MIT students would regularly devise. However, Levy's hacker ethic also has often been quoted out of context and misunderstood to refer to hacking as in breaking into computers, and so many sources incorrectly imply that it is describing the ideals of white-hat hackers. However, what Levy is talking about does not necessarily have anything particular to do with computer security, but addresses broader issues. The hacker ethic was described as a "new way of life, with a philosophy, an ethic and a
Item-item collaborative filtering Earlier collaborative filtering systems based on rating similarity between users (known as user-user collaborative filtering) had several problems: Item-item models resolve these problems in systems that have more users than items. Item-item models use rating distributions "per item", not "per user". With more users than items, each item tends to have more ratings than each user, so an item's average rating usually doesn't change quickly. This leads to more stable rating distributions in the model, so the model doesn't have to be rebuilt as often. When users consume and then rate an item, that item's similar items are picked from