Why do they call them "threads", if they are mere topics?

Because I'm new. And because I know that you'll welcome me. Anywho, my name is Dmitry, and my name is normally what I use for my online alias since at most forums I go to the names not taken, but when I tried registering here as 'Dmitry', it showed that the name was taken. So anyways, I chose the name Saberwing this time. I hope to enjoy learning whatever it is I'm going to learn here.