Index Finger - Wikipedia

A lone index finger held vertically is often used to represent the number 1 (but finger counting differs across cultures), or when held up or moved side to side (finger-wagging), it can be an admonitory gesture. If held upward, it can also mean "wait a minute" or "one moment". With the hand held palm out and the thumb and middle fingers touching, it represents the letter d in the American Sign Language alphabet.

Pointing

Pointing with the pointer finger may be used to indicate or identify an item, person, place or object.[4]

Around age one, babies begin pointing to communicate relatively complex thoughts, including interest, desire, and information. Pointing in human babies can demonstrate the theory of mind, or ability to understand what other people are thinking. This gesture may form one basis for the development of human language.

Non-human primates, lacking the ability to formulate ideas about what others are thinking, use pointing in much less complex ways.[5] However, corvids, dogs[6] and elephants[7] do understand finger pointing.

In some cultures, particularly the Malays and Javanese[8] in Southeast Asia, pointing using the index finger is considered rude, hence the thumb is used instead.

Index finger in Islam

In Islam raising the index finger signifies the Tawhīd (تَوْحِيد), which denotes the indivisible oneness of God. It is used to express the unity of God ("there is no god but God").

In Arabic, the index or fore finger is called musabbiḥa (مُسَبِّحة), mostly used with the definite article: al-musabbiḥa (الْمُسَبِّحة). Sometimes also as-sabbāḥa (السَّبّاحة) is used.[9][10] The Arabic verb سَبَّحَ - which shares the same root as the Arabic word for index finger - means to praise or glorify God by saying: "Subḥāna Allāh" (سُبْحانَ الله).

Index finger in archaeoastronomy

Before the advent of GPS and compass, early humans used index finger for pointing direction of objects with the help of stellar objects during night time.[11]