Excerpt, HuffPost blog :
"A lot of people have the wrong idea about introversion and confuse it with shyness. But shyness and introversion are not the same. As described by one neuroscientist I spoke to, shyness is behavior: acting fearful in social situations. Introversion is motivation: low drive to participate in social situations. So while shy people might want to socialize but find it intimidating, introverts have the skills but can take or leave socializing.
Also, you can overcome shyness if you want. Introversion seems to be hardwired, and it doesn’t need to be overcome. It’s fine as it is.
You can be shy and introverted, but you also can be not shy and introverted. (Same with extroversion. Shy extroverts have a hard time of it.)And introversion-extroversion, like other traits, exists on a continuum; you can be very introverted (or extroverted) or just a little.
Jung defined introversion in terms of energy: Extroverts are energized by time with other people, introverts are drained by it and crave copious time alone. While this theory lacks any empirical backing (what is this “energy” and how do we measure it?), introverts know what it means. Science will just have to catch up.”
~ Sophia Dembling, Nine Signs That You Might Be An Introvert