A widespread consensus on a partICular product or protocol whICh has not been ratified by any offICial standards body, such as ISO, but whICh nevertheless has a large market share. The archetypal example of a de facto standard is the IBM PC whICh, despite is many glaring technICal defICiencies, has gained such a large share of the personal computer market that it is now popular simply because it is popular and therefore enjoys fierce competition in prICing and software development. (1994-10-27)