It is called a ' BINDI '
Also loosely known as 'tika', 'pottu', 'sindoor', 'tilak', 'tilakam', and 'kumkum'
In southern India, girls choose to wear a bindi, while in other parts of India it is the prerogative of the married woman.
'Bindi' is derived from the Sanskrit word 'bindu' or a drop, and suggests the mystic third eye of a person, also 'Visesakachhedya', i.e., painting the forehead with a bindi or 'tilaka'.
How to apply one:
Traditional bindi is red or maroon in color. A pinch of vermilion powder applied skillfully with practiced fingertip make the perfect red dot. Women who are not nimble-fingered take great pains to get the perfect round. They use small circular discs or hollow pie coin as aid. First they apply a sticky wax paste on the empty space in the disc. This is then covered with kumkum or vermilion and then the disc is removed to get a perfect round bindi. Sandal, 'aguru', 'kasturi', 'kumkum' (made of red turmeric) and 'sindoor' (made of zinc oxide and dye) make this special red dot. Saffron ground together with 'kusumba' flower can also create the magic! http://hinduism.about.com/library/weekly/aa072002a.htm http://hinduism.about.com/library/weekly/aa072002b.htm