I started off life as a very shy introvert. Over the years, I've overcome much of my shyness. I love parties and events with lots of people, I speak comfortably in front of a group, and I enjoy performing. But I'm definitely still an introvert.
No, shyness and introversion are not one and the same. As I understand it, introverts recharge their mental, emotional, and spiritual energies by having time alone to be quiet and reflective. Extroverts are revitalized by spending time with others in conversation and collaboration. Conversely, introverts can be drained by too much time in social settings, while too much time by themselves can deplete an extrovert. There is, of course, a lot of variety along the spectrum of personalities.
After a very full and busy three days of social gatherings and outings, I'm feeling drained, for certain. I need time to be at home, quietly enjoying my down time. I will recharge by taking time for some writing, reading, and reflection. I enjoyed all of the activities I did this weekend, and wouldn't go back and undo any of them. Yet I can tell by my mental tension, a slight touch of emotional irritability, and some physical droopiness, that it's time to regroup. And I'm starting right now. A cup of tea and a book of sci-fi short stories await me. Enjoy your evening!