Anything that damages your hair can and will lead to split ends. Here are some ways we damage our hair every day.
Any kinds of chemicals are going to damage your hair to some extent, some hair types may suffer more damage than others. Chemicals from getting a perm, having your hair highlighted, colored, etc. or even chlorine in bath or pool water all count.
Brushing, Combing & Styling
Many people don't realize just how fragile the ends of hair are. Being too rough with a brush or comb, or brushing or combing too often can damage your hair. Excessive styling can also damage your hair, especially when "long hair unfriendly" hair accessories are used.
Soaking up the sun can feel so good, but being out in the sun with your hair unprotected can dry out your hair and make it brittle, leading to split ends.
Incorrect washing and washing with shampoos that are too harsh or contain certain ingredients can be damaging to your hair. The water you use to wash your hair may also be a culprit.
Rubbing your hair with a towel to dry it can cause nasty damage to your hair. Using a hairdryer on your hair too often will also cause damage.