Grey hat Grey hat The term "grey hat", alternatively spelled as "greyhat" or "gray hat", refers to a computer hacker or computer security expert who may sometimes violate laws or typical ethical standards, but does not have the malicious intent typical of a black hat hacker. The term began to be used in the late 1990s, derived from the concepts of "white hat" and "black hat" hackers. When a white hat hacker discovers a vulnerability, they will exploit it only with permission and not divulge its existence until it has been fixed, whereas the black hat will illegally exploit it and/or tell
Severin Hacker Severin Hacker Severin Hacker (born 1984) is a Swiss computer scientist who is the co-founder and CTO of Duolingo, a popular language-learning platform. Hacker was born and raised in Zug and studied at ETH Zurich. He moved to Pittsburgh to study at Carnegie Mellon University where he co-founded Duolingo with Luis von Ahn in 2009. He received his BS in Computer Science from ETH Zurich in 2006 and his PhD in Computer Science from Carnegie Mellon University in 2014. Initially, Hacker and his former graduate advisor, Luis von Ahn, wanted to develop an application that could translate internet sites, so