In India, you will find people wearing a red, yellow, orange and, rarely, a black mark on their forehead. It's called the tilak, or tilakam, in the Sanskrit language and is basically a Hindu tradition. Though it's commonly worn on the forehead, people also wear it on other parts of their body like neck, arms, chest and so on. Women generally wear the tilakam as a small dot on their forehead. Tilaka may be worn in India, either on a daily basis or on special religious occasions like a havan.
Indian tilak can be made by making a paste out of sandalwood paste, ashes, vermilion, clay or any other substance. There is a detailed description of the meaning and significance of the concept of tilak, along with the style of its application, in many Hindu mythologies. In the Indian state of Bihar, Nepal and other places, tilaka is also called tika or teeka. For Hindus, the tika is of utmost significance. Apart from being a decorative mark, it also indicates that the wearer belongs to a particular sect or social group.
Though the normal teeka is worn as a small dot on the forehead, there exist major variations in its application style. For instance, in case of certain sects in Hindu ascetics, the tilak may cover the entire forehead. As such, worn by priests, ascetics and normal devotees, it shows which Hindu tradition he follows. The Shaivites or the devotees of Lord Shiva typically use ash and draw their tilak as three horizontal lines. Vaishnavas (followers of Lord Vishnu) use clay from a holy river or place, which is sometimes mixed with sandalwood paste, as tilakam.
Indian women belonging to the Hindu community have been wearing the Tilaka for many millennia. The tilak they wear is generally a red round dot called the bindi, which signifies the fact that they are married. If the tilak is of any other color, then, most probably, it has been worn for a decorative purpose. The size of the bindi can vary from small to large. Hindu women who are married wear an additional tika between their hair-parting. This form of tilak is known as sindoor and it indicates her marital status.