What is Bindhi (A red dot that hindu men and women wear)?

Turmeric powder turns red to become bindi powder (kumkum) through a chemical reaction with an alkaline substance like slaked lime (calcium hydroxide) or borax. Curcumin, the natural yellow pigment in turmeric, acts as a pH indicator and shifts to a bright reddish-brown when exposed to a high-pH base. Hindus from ancient times had this technology about chemical reactions, etc. They were experts in Organic chemistry. 

Bindi generally always will be in RED color (naturally made). 
In modern times, women started changing the colors to different colors based on the color of their dress. 

There are several reasons for having Bindi on forehead:
  • Hindus believe that there is energy between the eyes that can easily be stolen by others. To distract them from doing it, they have bindi. It is worn by both men and women. This way, people don't hypnotize and to ward off evil eyes.
Forehead / Ajna → consciousness and spiritual awareness
Red → Shakti, life and auspiciousness
Kumkum → sacred substance used in worship
Bindi → placing that sacred symbolism on the body

So the traditional red bindi isn't simply decoration. Depending on the Hindu tradition, it can represent divine energy, auspiciousness, spiritual awareness, devotion, and—in some communities—a woman's married status.

Most women in India are considered Shakthi Swaroopinis (or those born with Shakthi or Energy).
So people used bindi to keep their shakthi within.

It is used by men and women for this purpose. Hinduism being superior in its approach to life, has mastered science some tens of thousands years back.

Why Hindus have temples and idols?

The reason for this is - "How can we open the 6th, 7th, 8th, and 9th sense of a person?"
Common people cannot meditate like Rishis (Sages who meditate 24x7 under a tree or on top of a rock or in forests). Common people have to work and are in-charge of their families. So, they do not have time to meditate and gain the knowledge beyond their daily grasp. 
So, temples were created using an advanced science.
  • Hindus take stones from the flowing waters. Why flowing waters because the stone beneath becomes smooth and as waters of rivers carry so many nutrients, the stones are already half-holy. 
  • Then they sculpt them into idols
  • Then they go through a scientific process called PRANA PRATISHTA (in other words initiate life into the stone) using sacred mantras (or hymns created to produce vibrations by priests who are vegetarian and go through immense day-to-day Nishta (or a series of disciplined ways of life with greatest devotion and commitment). 
  • After this process, this idol becomes VIGRAHA (A stone to idol to an object with life). 
  • When Hindus consecrate (establish the Vigraha in a temple) this VIGRAHA (another process done with Mantras in scientific way), the VIGRAHA reflects vibrations into our minds and opens up our 6th sense. 
  • When Hindus who are common people go to the temple and pray in front of the Vigraha, the object that is now with full of life bounces back the vibrations some thousands of times opening up the sixth sense and higher senses of a person faster. 
  • That is why Hindus have Temples and Vigraha to open the 6th sense and higher senses of the brain of a common man.
  • Also, the Theertha (holy water), the Aarathi (Camphor lighted), the Sadagopan (the cone shaped 5-metal object with the feet of the deity on top) on head, the bells made of Pancha (5) loha (metals), and the Vigraha all help in developing our 6th sense. 
Why 6th and higher senses?
If one opens up 6th sense, they will understand this world better.
They will know the difference between Good and Bad.
They will master those that our science cannot explain nor fathom.
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