> The best layman explanation I have heard is that extroverts are "recharged" by being around others whereas introverts recharge by being alone
That's a good step 1.
Step 2 is realising that introverts often do get energised by one-on-one or small group socialising, or socialising in a more meaningful way around a real shared interest.
Step 3 is realising that the concept of introversion/extraversion generalises past social interaction to preferences for levels of external interaction / stimulation in general. So for example, some people may not be super-sociable, but may love lot's of external physical stimulation (music/lights/exercise, etc), others may love to be exposed external ideas (or alternatively have a preference to only be exposed to small amounts of these things).
^ This is the notion of introversion/extroversion captured by the MBTI / Jungian Type Theories, where Extraverted Feeling (Fe) roughly function corresponds to the popular notion of extraversion, but there are also Extraverted Sensing (Se), Extraverted Intuition (Ne) and Extraverted Thinking (Te) functions which present differently.