Hacker is a term that has been used to mean a variety of different things in computing

Computing

Computing is usually defined as the activity of using and improving computer hardware and software. It is the computer-specific part of information technology...

. Depending on the context, the term could refer to a person in any one of several distinct (but not completely disjoint) communities and subculture

Subculture

In sociology, anthropology and cultural studies, a subculture is a group of people with a culture which differentiates them from the larger culture to which they belong.- Definition :...

s:People committed to circumvention of computer security. This primarily concerns unauthorized remote computer break-ins via a communication networks such as the Internet (Black hat

Black hat

A black hat is the villain or bad guy, especially in a western movie in which such a character would stereotypically wear a black hat in contrast to the hero's white hat, especially in black and white movies....

s), but also includes those who debug or fix security problems (White hats), and the morally ambiguous Grey hat

Grey hat

A grey hat, in the hacking community, refers to a skilled hacker whose activities fall somewhere between white and black hat hackers on a variety of spectra. It may relate to whether they sometimes arguably act illegally, though in good will, or to show how they disclose vulnerabilities...

s.