Aglets are the little metal or plastic ends on shoelaces and drawstrings. Since mine broke off from the drawstrings of my hoodie (OK, I chewed them off), I decided to wrap tread around the drawstrings to keep them from fraying at the ends. It turned out to be pretty simple and only took about half an hour to finish both ends.
Look at the second picture. See how frayed that is? Let's fix it. First, thread a needle. If you don't know how, check out this instructable. You will want about two feet of thread, about the same color as the drawstring. Next, thread the needle through part of the drawstring, and tie it off. Now we're ready to start wrapping.