An ethical hacker is a computer security expert who uses his or her skills in a legal and authorised manner to test and improve the security of computer systems.
It is often referred to as a pentester because it makes pentests.
An ethical hacker is a "white hat" hacker, as opposed to a "black hat" hacker, who has malicious intentions.
To find out more (skills, salary, etc.), read the article
Pentester, an ethical hacker who protects your company
