Because even if someone manages to get one or two of them right, they seldom get them all:
Hacker – n. 1. Originally used in the 1970’s to refer to someone who was such a good programmer they could write code without referring to reference materials. This was a much bigger feat back then, when you consider they were essentially working with a text editor. 2. In the eighties, it became anyone who could gain access, through physical or social means, to a computer system they had no permission to be on. They were usually not destructive, and were simply “counting coup*”. 3. By the 1990’s, the term came to refer to any person doing something not legal with a computer, but for the most part it dropped the social engineering aspect and relies primarily on computer knowledge and use of software.
Phreaker (a.k.a Phone Phreak) – n. 1. Someone who through use of technology such as a tone-generator or social engineering manages to obtain free telephone service, usually through public pay phones.
Cracker – n. 1. Someone who is primarily known for breaking the copy protection on software.
Script Kiddie – n. 1. A person with little or no programming knowledge or skill, who uses tools constructed by someone else to launch destructive or disabling attacks on computers over the Internet.
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*Counting Coup – v. 1. Associated with American Indian Plains culture. A ritual stick is used by a warrior to touch (not kill or maim) an armed enemy. transfers highest honor and status to touch an enemy who has weapons while you are only armed with a ritual stick.