The term white hat hacker is also often used to describe those who attempt to break into systems or networks in order to help the owners of the system by making them aware of security flaws, or to perform some other altruistic activity for monetary gain or charity. Many such people are employed by computer security companies; these professionals are sometimes called sneakers. Groups of these people are often called tiger teams.
The primary difference between white and black hat hackers is that a white hat hacker observes ethical principles. Like black hats, white hats are often intimately familiar with the internal details of security systems, and can delve into obscure machine code when needed to find a solution to a tricky problem. Some use the term grey hat and fewer use brown hat to describe someone's activities that cross between black and white.
Source :Wikipedia
