Ethical Hacking

White Hat/Black Hat/Gray Hat

White Hat Hacker:

White Hat hackers are good guys who does the hacking for defensing.  They probably work an organization for providing security.

Black Hat Hacker

Black hat hackers are bad guys(the malicious hackers or crackers).  They usually steal the other bank information and steal the money. 
They use their skills for illegal purposes.
They are creators of viruses,malware,spyware.
They will destroy your pc.

Gray Hat Hackers

Grey hats are hackers who may work offensively or defensively, depending on the situation.
This is the dividing line between hacker and cracker. Both are powerful forces on the Internet,
and both will remain permanently. And some individuals qualify for both categories. The
existence of such individuals further clouds the division between these two groups of people.
In addition to these groups, there are self-proclaimed ethical hackers, who are interested in
hacker tools mostly from a curiosity standpoint. They may want to highlight security problems
in a system or educate victims so they secure their systems properly. These hackers are
doing their “victims” a favor. For instance, if a weakness is discovered in a service offered by
an investment bank, the hacker is doing the bank a favor by giving the bank a chance to rectify
the vulnerability.