We can all see split ends when they happen but do you actually know what they are and what causes them? Split ends (or trichoptilosis, to get fancy and scientific) occur when the cuticle, the protective outer layer of each hair strand, gets stripped away and the dry, vulnerable hair underneath splits. Although there are lots of "split-end mending" products out there, fixing them actually isn't possible, so once you've got 'em, you've got to cut them off.
The only way to avoid split ends is to prevent them. This means deep conditioning, not over-colouring your hair and easing up on the use of heated styling tools. If this isn't possible, you can still help safeguard your hair by using a treatment that structurally reinforces it, like Surya Restorative Serum for Split Ends ($17.60), and by getting your hair trimmed regularly.