A bindi (Hindi: बिंदी, from Sanskrit बिन्दु bindú meaning "point, drop, dot or small particle") or pottu (Tamil : பொட்டு)   is a coloured dot or, in modern times, a sticker worn on the center of the forehead, originally by Hindus, Jains, Buddhists, and Sikhs from the Indian subcontinent.
A bindi is a bright dot of some colour applied in the centre of the forehead close to the eyebrows or in the middle of the forehead that is worn in the Indian subcontinent (particularly amongst Hindus in India, Pakistan, Bangladesh, Nepal, Bhutan, and Sri Lanka)  and Southeast Asia among Balinese, Filipino, Javanese, Sundanese, Malaysian, Singaporean, Vietnamese, and Myanmarese Hindus. A similar marking is also worn by babies and children in China and, as in the Indian subcontinent and Southeast Asia, represents the opening of the third eye.  In Hinduism, Buddhism, and Jainism the bindi is associated with the ajna chakra, and Bindu  is known as the third eye chakra. Bindu is the point or dot around which the mandala is created, representing the universe.   The bindi has a historical and cultural presence in the region of Greater India.  
Traditionally, the area between the eyebrows (where the bindi is placed) is said to be the sixth chakra, ajna , the seat of "concealed wisdom". The bindi is said to retain energy and strengthen concentration.  The bindi also represents the third eye.  The Nasadiya Sukta of the Rig Veda, the earliest known Sanskrit text, mentions the word Bindu . 
The Ajna is symbolised by a sacred lotus with two petals, and corresponds to the colours violet, indigo or deep blue, though it is traditionally described as white. It is at this point that the two sides Nadi Ida (yoga) and Pingala are said to terminate and merge with the central channel Sushumna, signifying the end of duality, the characteristic of being dual (e.g. light and dark, or male and female). The seed syllable for this chakra is the syllable OM, and the presiding deity is Ardhanarishvara, who is a half male, half female Shiva/Shakti. The Shakti goddess of Ajna is called Hakini. In metaphysics, Bindu is considered the dot or point at which creation begins and may become unity. It is also described as "the sacred symbol of the cosmos in its unmanifested state".   Bindu is the point around which the mandala is created, representing the universe.  Ajna (along with Bindu), is known as the third eye chakra and is linked to the pineal gland [ clarification needed ] which may inform a model of its envisioning. The pineal gland is a light sensitive gland that produces the hormone melatonin which regulates sleep and waking up, and is also postulated to be the production site of the psychedelic dimethyltryptamine, the only known hallucinogen endogenous to the human body. Ajna's key issues involve balancing the higher and lower selves and trusting inner guidance. Ajna's inner aspect relates to the access of intuition. Mentally, Ajna deals with visual consciousness. Emotionally, Ajna deals with clarity on an intuitive level. 
In Hinduism, Buddhism, and Jainism, bindi is associated with Ajna Chakra and Bindu.  Divinities in these religions are typically depicted with Bhrumadhya Bindu , in meditative pose with their eyes nearly closed show the gaze focused between eyebrows, other spot being the tip of the nose—Naasikagra. The very spot between the eyebrows known as Bhrumadhya is where one focuses one's sight, so that it helps concentration.  In South Asia, bindi is worn by women of all religious dispositions and is not restricted to religion or region. However, the Islamic Research Foundation, located in India, says "wearing a bindi or mangalsutra is a sign of Hindu women. The traditional bindi still represents and preserves the symbolic significance that is integrated into Indian mythology in many parts of India."
The red bindi has multiple meanings:
A traditional bindi is red or maroon in colour. A pinch of vermilion powder is applied with a ring-finger to make a dot. A small annular disc aids application for beginners. First, a sticky wax paste is applied through the empty centre of the disc. This is then covered with kumkum or vermilion and then the disc is removed to get a round bindi. Various materials such as lac, sandal, 'aguru', mica, 'kasturi', kumkum (made of red turmeric) and sindoor color the dot. Saffron ground together with 'kusumba' flower can also work.  Traditionally they are green in color with a red dot in the middle.  The bindi is no longer restricted in color or shape.  
Historically, the ornamental bindi spangle consists of a small piece of lac over which is smeared vermilion, while above it a piece of mica or thin glass is fixed for ornament. Women wore large spangles set in gold with a border of jewels if they could afford it. The bindi was made and sold by lac workers known as Lakhera.  In Hinduism, it's part of the Suhāg or lucky trousseau at marriages and is affixed to the girl's forehead on her wedding and thereafter always worn.  Unmarried girls optionally wore small ornamental spangles on their foreheads. A widow was not allowed to wear bindi or any ornamentation associated with married women.  In modern times, self-adhesive bindis are available in various materials, usually made of felt or thin metal and adhesive on the other side. These are simple to apply, disposable substitutes for older lac tikli bindis. Sticker bindis come in many colours, designs, materials, and sizes.
There are different regional variations of the bindi. In Maharashtra a large crescent moon shaped bindi is worn with a smaller black dot underneath or above, associated with Chandrabindu and Bindu chakra represented by crescent moon, they are commonly known as Chandrakor in this region, outside Maharashtra they are popularly known as Marathi bindi. In Bengal region a large round red bindi is worn, brides in this region are often decorated with Alpana design on forehead and cheeks, along with bindi. In southern India a smaller red bindi is worn with a white tilak at the bottom, another common type is a red tilak shaped bindi. In Rajasthan the bindi is often worn round, long tilak shaped bindi are also common, as well as the crescent moon on some occasions. Decorative bindis have become popular among women in South Asia, regardless of religious background. Bindis are a staple and symbolic for women in the Indian subcontinent. 
In addition to the bindi, in India, a vermilion mark in the parting of the hair just above the forehead is worn by married women as commitment to long-life and well-being of their husbands. During all Hindu marriage ceremonies, the groom applies sindoor in the part in the bride's hair. 
Apart from their cosmetic use, bindis have found a modern medical application in India. Iodine patch bindis have often been used among women in north-west Maharashtra to battle iodine deficiency. 
In Southeast Asia, bindis are worn by the Balinese, Javanese, and Sundanese people of Indonesia. For example, bindis are often worn by brides and grooms in Java and other parts of Indonesia, regardless of their religious beliefs.
The Indonesian practice of wearing a bindi originated from the cultural influence brought about by the Indianized Hindu kingdoms that once ruled Indonesia. Historically, other Indianized kingdoms in Southeast Asia also took part in this practice.
Bindis are sometimes worn purely for decorative purpose or style statement without any religious or cultural affiliation.  Decorative and ornamental bindis were introduced to other parts of the world by immigrants from the Indian subcontinent.  International celebrities such as Gwen Stefani, Julia Roberts,  Madonna,  Selena Gomez and many others have been seen wearing bindis.  The appropriateness of such uses has been disputed. Reacting to Gomez wearing a bindi while singing her song "Come and Get It", Hindu leader Rajan Zed said that the bindi has religious significance and should not be used as a fashion accessory,  but Indian actress Priyanka Chopra praised Gomez's choice as "an embrace of Indian culture".  Additionally, several rappers have adopted jewelled bindis, most notably Lil Uzi Vert, who debuted a $24 million pink diamond bindi in February 2021. They were inspired by Lil B who wore a diamond bindi in 2012. 
Bindis are part of Bangladeshi culture and women in Bangladesh, irrespective of their religion, adorn themselves with bindis as an ethnic practice.    In Pakistan, bindis are worn by some Muslim girls during Eid, though they are ordinarily worn by Hindu women in the Punjab and Sindh. 
A bindi can also be called: 
Hindus are people who religiously adhere to Hinduism. Historically, the term has also been used as a geographical, cultural, and later religious identifier for people living in the Indian subcontinent.
The third eye is a mystical invisible eye, usually depicted as located on the forehead, which provides perception beyond ordinary sight. In Hinduism, the third eye refers to the ajna chakra. In both Hinduism and Buddhism, the third eye is said to be located around the middle of the forehead, slightly above the junction of the eyebrows, representing the enlightenment one achieves through meditation.
Indian culture is the heritage of social norms and technologies that originated in or are associated with the ethno-linguistically diverse India. The term also applies beyond India to countries and cultures whose histories are strongly connected to India by immigration, colonisation, or influence, particularly in South Asia and Southeast Asia. India's languages, religions, dance, music, architecture, food and customs differ from place to place within the country.
Ajna, brow or third eye chakra, is the sixth primary chakra in the body according to Hindu tradition and signifies the unconscious mind, the direct link to Brahman. The third eye is said to connect people to their intuition, give them the ability to communicate with the world, or help them receive messages from the past and the future.
In Hinduism, vibhuti, also called bhasma or tirunīru, is sacred ash made of burnt dried wood, burnt cow dung and/or cremated bodies used in Agamic rituals. Hindu devotees apply vibhuti traditionally as three horizontal lines across the forehead and other parts of the body to honour Shiva. Vibhuti smeared across the forehead to the end of both eyebrows is called tripundra.
Sindooram is a traditional vermilion red or orange-red coloured cosmetic powder from the Indian subcontinent, usually worn by married women along the part of their hairline. In Hindu communities the sindoor is a visual marker of marital status of a woman and ceasing to wear it usually implies widowhood.
Bindu is a Sanskrit word meaning "point", "drop" or "dot".
In Hinduism, the tilaka is a mark worn usually on the forehead, at the point of the Ajna chakra, or sometimes another part of the body such as the neck, hand, chest, or the arm. The tilaka may be worn daily or for rites of passage or special spiritual and religious occasions only, depending on regional customs.
Thirunamam represents the 'Sacred name of God'. The phrase Namam also represents the white clay found at the deeper layer of earth, which is used as the powder to wear a flame shaped mark. The Ayyavazhi people wore this Namam, starting from the central point between the eyebrows, going straight up near the top edge of the forehead.
Kumkuma is a powder used for social and religious markings in India. It is made from turmeric or any other local materials. The turmeric is dried and powdered with a bit of slaked lime, which turns the rich yellow powder into a red color.
Khada dupatta is the traditional wedding dress of Hyderabadi Muslim brides in the Indian subcontinent. It is an elaborate wedding ensemble comprising a kurta (tunic), chooridaar, and a 6-yard dupatta.
The Dotbusters was a Hinduphobic hate group active in Jersey City, New Jersey from 1975 to 1993 that attacked and threatened Indian Americans, particularly Indians in the fall of 1975. The name originated from the fact that traditional Hindu women and girls wear bindis on their foreheads.
Yantra (यन्त्र) is a geometrical diagram, mainly from the Tantric traditions of the Indian religions. Yantras are used for the worship of deities in temples or at home; as an aid in meditation; used for the benefits given by their supposed occult powers based on Hindu astrology and tantric texts. They are also used for adornment of temple floors, due mainly to their aesthetic and symmetric qualities. Specific yantras are traditionally associated with specific deities and/or certain types of energies used for accomplishment of certain tasks, vows, that may be materialistic or spiritual in nature. It becomes a prime tool in certain sadhanas performed by the sadhaka the spiritual seeker. Yantras hold great importance in Hinduism, Jainism, and Buddhism.
The Urdhva Pundra is a tilaka worn by Vaishnavas as an indication of their affiliation with Vishnu. It is generally worn on the forehead, but may also be worn on other parts of the body such as the shoulders. The markings are made either as a daily ritual, or on special occasions, and denote the particular sampradaya, or the lineage to which the devotee belongs. The different Vaishnava sampradayas each have their own distinctive style of tilaka based on the siddhanta of their particular lineage. The general tilaka design is of two or three vertical lines resembling the letter U, which represent the feet of Vishnu.
Paduka is an ancient form of footwear in India, consisting of a sole with a post and knob which is positioned between the big and second toe. It has been historically worn in South Asia and Southeast Asia. Paduka exist in a variety of forms and materials. They might be made in the shape of actual feet, or of fish, for example, and have been made of wood, ivory and silver. They may be elaborately decorated, such as when used as part of a bride's trousseau, but could also be given as religious offerings or themselves be the object of veneration.
Worship in Hinduism is an act of religious devotion usually directed to one or more Hindu deities. A sense of Bhakti or devotional love is generally invoked. This term is probably a central one in Hinduism, but a direct translation from the Sanskrit to English is difficult. Worship takes a multitude of forms depending on geography and language. Worship is not confined to any place of worship, and it will often incorporate personal reflection, music, dance and poetry. Hindus usually perform worship in temples or at home to achieve some specific end or to integrate the body, mind and spirit. The aim is to live a pure life in order to help the performer reincarnate into a higher being.
Tripundra is a Hindu Shaivite tilaka, and a form of body art with origins in Ancient India. It is also one of the tilakas worn by Smarta Hindus. It consists of three horizontal lines on the forehead, usually made with sacred ash, and has spiritual meanings in the Shaivite traditions of Hinduism. The Vaishnava counterpart of this tilaka, consisting of vertical lines, is called the Urdhva Pundra.
Over the millennia of its development, Hinduism has adopted several iconic symbols, forming part of Hindu iconography, that are imbued with spiritual meaning based on either the scriptures or cultural traditions. The exact significance accorded to any of the icons varies with region, period and denomination of the followers. Over time some of the symbols, for instance the Swastika has come to have wider association while others like Om are recognized as unique representations of Hinduism. Other aspects of Hindu iconography are covered by the terms murti, for icons and mudra for gestures and positions of the hands and body.
borrowed from Hindi bindī, literally, "dot, mark" (or a cognate Indo-Aryan word), going back to the Middle Indo-Aryan and Sanskrit stem bindu- "drop, spot," it's worn by Sikhs, Buddhist, Jains and Hindus
English word bindi comes from Hindi बिंदी