What is a hacker and what is ethical hacking??

Currently, "hacker" is used in two main ways,one pejorative and one complimentary.In popular usage and in the media,it most often refers to computer intruders or criminals, with associated pejorative connotations. (For example, "An Internet 'hacker' broke through state government security systems.In the computing community, the primary meaning is a complimentary description for a particularly brilliant programmer or technical expert.(For example, "Linus Torvalds,the creator of Linux, is considered by some to be a genius 'hacker'(Ethical Hacker).") By the way for more information on Ethical Hacker check this link: http://www.eccouncil.org/certification/certified_ethical_hacker.aspx