A hacker is a person skilled in information technology who achieves goals by non-standard means. The term has become associated in popular culture with a security hacker – someone with knowledge of bugs or exploits to break into computer systems and access data which would otherwise be inaccessible to them. In a positive connotation, though, hacking can also be utilized by legitimate figures in legal situations. For example, law enforcement agencies sometimes use hacking techniques to collect evidence on criminals and other malicious actors. This could include using anonymity tools to mask their identities online and pose as criminals. Likewise, covert world agencies can employ hacking techniques in the legal conduct of their work. Hacking and cyber-attacks are used extra-legally and illegally by law enforcement and security agencies, and employed by state actors as a weapon of legal and illegal warfare.

A security hacker is someone who explores methods for breaching defenses and exploiting weaknesses in a computer system or network. Hackers may be motivated by a multitude of reasons, such as profit, protest, information gathering, challenge, recreation, or evaluation of a system weaknesses to assist in formulating defenses against potential hackers.