Once again I should begin this post with a very simple explanation of what makes introvert and extrovert different. Introversion means that you get your energy recharged by alone time. Extroversion means you get your energy recharged by being around other people. You are either born an introvert or an extrovert. There is no right or wrong way to be.
I have always enjoyed writing more than talking. I believe it has to do with my being an introvert. My thoughts simply flow much better in black on white than it does when I am trying to formulate my thoughts verbally. I always end up in a jumble of incoherent words.
This is why I also prefer texting over phone calls.
Other article on introversion: