Hackers and Crackers

A second threat on the Internet, though rare compared to viruses, are hackers and crackers. These are people (or more likely computers) that sneak stuff into your computer through open ports in your Internet connection. Hacking in real life isn’t at all like it is in movies. In movies, some good-looking young kids take two or three guesses at some password and magically have access to the entire computer. In real life, it doesn’t work that way at all. Nobody can break into your computer and steal things or even look around.

The kind of hacking that takes place on computers is almost always done by computers, not humans. Some human programmer creates a program that just wanders around the Internet looking for open ports, sneaking some virus-type program onto a computer’s hard disk without the owner knowing it. This is a slow and tedious way to infect multiple computers and therefore isn’t done much. But it is done, and you need to have some protection. The type of program you use to protect your computer from hackers is called a firewall. It actually works on a very simple principle. Normally, your computer will just accept anything that comes in off the Internet, under the assumption that if there’s something coming in from the Internet, you must have requested it. That’s the very assumption that enables hackers to sneak things onto your computer.

The press and the general public use the terms hacker and cracker interchangeably, despite the fact that doing so irritates the daylights out of computer programmers.
In the programming world, hacker is a slang term for programmer. The vast majority of programmers in the world never write any code that would damage a computer or replicate itself, and they don’t like being put in the same category as those who know just enough programming to take some existing virus and tweak it into something else (not at all impressive to a real programmer).

Programmers refer to people who do bad things with their programming skills as crackers, not hackers. Cracker has its origins in the idea of a safecracker, one who breaks into safes. But these programmers don’t break into safes. They break into computers and networks where they don’t belong, stealing corporate secrets or just wreaking random havoc.

Source of Information : Wiley Alan Simpsons Windows Vista Bible Desktop Edition