A hacker originally meant someone who likes to do new things with computers. Now hacker is used to mean "someone who tries to get into another person's computer using computer software such as Trojan horse programs, computer viruses, and worms that can hurt other people computers". The correct name for a person doing these illegal things was cracker, but many news stories used the word hacker even though it was in error. Another meaning of hacker is someone who can change or program something, like how people can change or program a Furby to say something insulting or humorous.
A person doing something illegal with a computer belonging to someone else without asking a permission of the owner is also called a hacker.
In the recent years computers were becoming increasingly more complex. This also means that people with bad intentions have more opportunities to use them for criminal purposes. Computer engineers aren't always able to find vulnerable places in the computer code. Hackers find such places, and use them.
There are also hackers who use the same skills for good purposes. Such hackers are called white hat hackers. They help computer engineers to find vulnerable places and correct problems.
A lot of skills are often required to be a hacker. A hacker should be able to find problems or solutions that most other people cannot find.
- Manthan M Desai, Hacking For Beginners: a beginners guide to learn ethical hacking, hackingtech.co.tv Revised Android Edition (Ht Hackingtech, 2012), p. 13