The hacker culture is a subculture of individuals who enjoy—often in collective effort—the intellectual challenge of creatively overcoming the limitations of software systems or electronic hardware, to achieve novel and clever outcomes. The act of engaging in activities in a spirit of playfulness and exploration is termed hacking. However, the defining characteristic of a hacker is not the activities performed themselves, but how it is done and whether it is exciting and meaningful. Activities of playful cleverness can be said to have "hack value" and therefore the term "hacks" came about, with early examples including pranks at MIT done by students to demonstrate their technical aptitude and cleverness. The hacker culture originally emerged in academia in the 1960s around the Massachusetts Institute of Technology (MIT)'s Tech Model Railroad Club (TMRC) and MIT Artificial Intelligence Laboratory. Hacking originally involved entering restricted areas in a clever way without causing any major damage. Some famous hacks at the Massachusetts Institute of Technology were placing of a campus police cruiser on the roof of the Great Dome and converting the Great Dome into R2-D2.

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.