1) An individual who writes programs in various assembly languages and/or system-level languages.2) An individual that gains unauthorized access to computer systems for the purposes of stealing and/or corrupting data within that computer system.The term hacker has both positive and negative connotations. It can refer to someone who is a programmer and has knowledge of assembly or system-level languages, or it can mean a person who tries to crack another person's computer system with the intent to do it harm.