Usability Professionals' Association was created in 1991.
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The Chambers Dictionary says usable.
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"Usability is a term used to denote the ease with which people
can employ a particular tool or other human-made object in order to
achieve a particular goal. Usability can also refer to the methods
of measuring usability and the study of the principles behind an
object's perceived efficiency or elegance."
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The author of 'Prioritizing Web Usability' is Jakob Nielsen.
Nielsen, a usability consultant, was born in Copenhagen, Denmark in
1957. He holds a Ph. D. in human-computer interaction.