The most typical visible may be the pale nerd in his mother's attic who is hacker for hire into his university machine to change his rivals qualities to failing ones. Then there are the various Hollywood depictions which show "master criminals" influencing traffic signs and financial markets. This can be a rather new use of the word "hacker" and for decades before it had a different meaning.
In the first 90's when Linux (a common free computer operating system) was presented, the term hacker didn't also exist. People of the operating systems known themselves as "hackers", just for their ability to govern and reuse coding code for their very own purposes, beyond its formerly supposed purpose. If you believe of them as cooks, everybody has that certain fundamental menu for seafood bisque, but each cook may set their own spin on the recipe to make it their own. They certainly were / are very capable programmers that had a passion for writing their own programs.
The majority of these "hackers" used their abilities for good. For instance, supporting a buddy who needed new computer software to hold monitoring of catalog at a grocery store. Then there are some more famous hackers, including Charlie Careers and Bill Gates who produced a fortune creating a client pc for the home. A tiny percentage used their skills at under respectable applications, such as Kevin Poulsen and Adrian Lamo. These dishonorable hackers are what gave the respectable activity of computer adjustment their bad name.
Because of the large amount of media interest on the subject, lately, the definition of "hacker" has become associated with crime and persons utilizing their abilities to grab and develop fear. While this can be correct in certain situations, it is not the majority. Now we distinguish great from wicked with (figurative) hats: