In the near past I have been attacked by what I call informatic pirates. They attacked my computer so that I had to format its disk and replace the existing version of the operating system. My computer is an Apple MacBook Pro.
Hacker is a term used by some to mean "a clever programmer" and by others, especially those in popular media, to mean "someone who tries to break into computer systems."
Eric Raymond, compiler of The New Hacker's Dictionary, defines a hacker as a clever programmer. A "good hack" is a clever solution to a programming problem and "hacking" is the act of doing it. Raymond lists five possible characteristics that qualify one as a hacker, which we paraphrase here:
A person who enjoys learning details of a programming language or system
A person who enjoys actually doing the programming rather than just theorizing about it
A person capable of appreciating someone else's hacking
A person who picks up programming quickly
A person who is an expert at a particular programming language or system, as in "UNIX hacker"
The hacker will "take over" your computer as if he was sitting in front of it like you. Then the phone will ring telling you that there is a virus in your computer and he can fix it if you pay him so much money ($ 200 or $ 500 depending on how long you want the service to last, but this is all fake).
What you have to do then is to turn your computer off. when you start it again everything may be normal, but if the hacker is still there, then you take your computer to a computer place (around here it would be Staples store) and the expert there will tell you that you need to clean your computer - it takes a day or two and costs about $ 50. In that process it is possible that the expert will create extra storage in your computer (it found about 10 Giga space in mine).