From The Art and Popular Culture Encyclopedia
The index finger, (also referred to as forefinger, pointer finger, trigger finger, digitus secundus, digitus II is the first finger and the second digit of a human hand. It is located between the first and third digits, between the thumb and the middle finger. It is usually the most dextrous and sensitive finger of the hand, though not the longest – it is shorter than the middle finger, and may be shorter or longer than the ring finger – see digit ratio.
"Index finger" literally means "pointing finger", from the same Latin source as indicate; its anatomical names are either "index finger" or "second digit".
A lone index finger held vertically is often used to represent the number 1, or when held up or moved side to side (finger-wagging), it can be an admonitory gesture. With the hand held palm out and the thumb and middle fingers touching, it represents the letter d in the American Sign Language alphabet. In sports, it can also represent victory, as some championship-winning teams raise their index finger (often saying "We're number one!") while posing for a championship team photo – oversized foam hands with a single upraised index are also used for this purpose; compare with the victory sign. For the vast majority of computer users, it is the finger most often used to click a mouse, as well as the finger used in the untrained 'hunt and peck' Typing style.
Pointing one's index finger at a person is considered rude in certain cultures. A more polite way to indicate another person would be to raise a hand in their direction, as if holding a platter.
- Michelangelo's Finger: An Exploration of Everyday Transcendence (2010) by Raymond Tallis.