A hacker is most commonly a person who seeks unauthorized access to a computer system or network. The word is also used for a skilled programmer or computer enthusiast. In computer security, it may describe an intruder or an authorized specialist who tests systems and reports vulnerabilities. Programmer and free software communities apply the term to people who explore programmable systems, modify software, or find ways around technical limits. Its meaning depends on context, and communities disagree over who may claim it.