What causes the fuzzy lint at the bottom of my shirt?

I recently wore a new shirt and I've noticed (along with all my other shirts) that on the back bottom part, there's like little lint that aren't removable. The whole backside has like this fuzzy quality compared to the rest of the shirt and there's of lint I guess, but when I try to pick them out, like parts of the threads (?) pull off with it. What are these and how can I prevent them? I didn't even wash this shirt yet, how did this happen?