Security hacker that members of the computer underground should be called crackers. Yet, those people see themselves as hackers and even try to include the views of Raymond in what they see as a wider hacker culture, a view that Raymond has harshly rejected. Instead of a hacker/cracker dichotomy, they emphasize a spectrum of different categories, such as white hat, grey hat, black hat and script kiddie. In contrast to Raymond, they usually reserve the term "cracker" for more malicious activity. According to Ralph D. Clifford, a "cracker" or "cracking" is to "gain unauthorized access to a computer in order to commit
Severin Hacker that that it would be accessible for non-English speakers. They felt that automated translation software wasn't as effective as using the skills and knowledge of bilingual speakers. During Hacker's doctoral studies, Duolingo became a by-product of this idea, or "happy mistake." Hacker's goal for Duolingo was to make it "100% free" so the most disadvantaged person with an internet connection would still have access to it. Hacker and his team of PhD students used machine learning to personalize Duolingo to each user. Specifically, they wanted to predict what language concepts the user was on the verge of forgetting. In 2012,