Extroverted describes someone who's outgoing and social. Your extroverted friend wants to go to out and meet people, but your other friend would rather do the opposite — stay home and read books.
First used in modern psychology around 1918, the adjective extroverted has origins in the German word extra, meaning "outward," and the Latin word vertere, meaning "to turn." So extroverted people look outward rather than toward their inner thoughts. They're outgoing, expressive, and interested in what's going on around them. If you're extroverted, you probably enjoy parties and can move through the room with ease chatting with everyone whether you know them or not.