hi frnds,,
Today post is on d topic  wch is asked by many people what d exact mean of hacker n wat is his wrk???
So , here i clerify what d exact is hacker is:
Hacker. Now here is an interesting word. Originally the term in Yiddish meant “inept furniture
maker.”Today, the term has many different meanings, both good and bad. On the good side, the hacker
is a creative individual who knows the details of computer systems and how to stretch their capabilities
to deliver speedy solutions to seemingly complex information demands. On the bad side, the
hacker—more appropriately termed a cracker—is a malicious meddler in computer systems who is
out to deface, replace, or delete data for personal gain, to sabotage a system, to get revenge, or to bring
down the economic and social well-being of a nation by attacking its highly networked critical infrastructures.
 And  basically Hackers are of 3 types i.e. WHITE, BLACK AND GREY HAT hacker.
The first one is the 
black hat, also
 known as a
 cracker, someone who  uses his computer knowledge in criminal activities in order to obtain  personal benefits. A typical example is a person who exploits the  weaknesses of the systems of a financial institution for making some  money.
On the other side is the 
white hat hacker. Although white hat hacking  can be considered similar to a black hacker, there is an important  difference. A white hacker does it with no criminal intention in mind.  Companies around the world, who want to test their systems, contract  white hackers. They will test how secure are their systems, and point  any faults that they may found. If you want to become a hacker with a  white hat, linux, a PC and an internet connection is all you need.
A 
grey hat hacker is someone who is in between these two concepts. He  may use his skills for legal or illegal acts, but not for personal  gains. Grey hackers use their skills in
order to prove themselves that they can accomplish a determined feat,  but never do it in order to make money out of it. The moment they cross  that boundary, they become black hackers.
For example, they may hack the computer network of a public agency, let us say, NOAA. That is a federal crime.
If the authorities capture them, they will feel the long arm of justice.  However, if they only get inside, and post, let us say, their handle,  and get out without causing any kind of damage, then they can be  considered grey hackers.