In color theory, a purple is defined as any non-spectral color between violet and red (excluding violet and red themselves). The spectral colors violet and indigo are not purples according to color theory, but they are purples according to common English usage since they are between red and blue.
Apex Learning was started in 1997 by Microsoft co-founder Paul Allen on the idea that online courses and test prep, which were already succeeding in higher education, could be applied to K-12.
History [edit]. Windchill was originally developed by Windchill Technology Inc., which was co-founded by Jim Heppelmann, the current President and CEO of PTC. When PTC acquired Windchill Technology, Heppelmann joined the company as senior vice president. Windchill first launched in 1998 and was promoted as the first to market with an internet based PLM solution.