In computing, a hacker is any skilled computer expert that uses their technical knowledge to overcome a problem. While "hacker" can refer to any computer programmer, the term has become associated in popular culture with a "security hacker", someone who, with their technical knowledge, uses bugs or exploits to break into computer systems.
Hacker culture is an idea derived from a community of enthusiast computer programmers and systems designers in the 1960s around the Massachusetts Institute of Technology's (MIT's) Tech Model Railroad Club (TMRC) and the MIT Artificial Intelligence Laboratory. The concept expanded to the hobbyist home computing community, focusing on hardware in the late 1970s (e.g. the Homebrew Computer Club) and on software (video games,software cracking, the demoscene) in the 1980s/1990s. Later, this would go on to encompass many new definitions such as art, and Life hacking.
Security hackers are people involved with circumvention of computer security. Among security hackers, there are several types, including:
White hats are hackers who work to keep data safe from other hackers by finding system vulnerabilities that can be mitigated. White hats are usually employed by the target system's owner, and are typically paid (sometimes quite well) for their work. Their work is not illegal, because it is done with the system owner's consent.