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.
He is the founder of the Khan Academy, a free online education platform and an organization with which he has produced over 6,500 video lessons teaching a wide spectrum of academic subjects, mainly focusing on mathematics and sciences.