The index finger is the finger next to your thumb, the one you naturally point with when showing someone a direction or picking out something specific. It's called the index finger because “index” means to point out or indicate something, and this finger does exactly that.

Your index finger is incredibly useful. When you press a doorbell, tap a keyboard, or scroll on a tablet, you're probably using your index finger. It's the finger that traces along the page when you're reading something carefully, or the one you raise when you want to ask a question in class. When someone says “put your finger on it,” they usually mean this finger, because it's one of the most precise and controlled fingers for pointing and touching.

The index finger is also called the forefinger or the pointer finger. In many cultures, pointing with your index finger is a natural gesture, though it's considered rude in some places to point directly at people.