I believe it comes from Meyers Briggs (sp?), the MBTI personality assessment. On some level it's not wrong to suggest this is an observable component of personalities. But it's a bit aggressive to assert that this is the sole definition of the word.

More pseudo-science touted as fact. It's the programmer's Horoscope. I know people (plural), IRL who laugh at horoscopes and then spout MB horseshit with a straight face.

E-spells

I think the MB framework is decent. The issue is that the test is noisy, is context dependent, unstable, and a middle value isn't well defined. But the tail ends are very interesting, relevant ways to categorize personality.

If you forget the test and just consider the ideas, it's useful

The idea isn't new; it came from Carl Jung [1], who coincidentally also coined the terms "introvert" and "extrovert". I don't believe his notions of "psychic energy" are taken seriously by the scientific establishment of today.

[1] https://www.psychologistworld.com/influence-personality/extr...