Rangoli is one of the most popular art forms in India. It is a form of sand painting decoration that uses finely ground white powder and colors, and is used commonly outside homes in India. A rangoli painted on the occasion of Diwali, a popular Hindu festival.
Originally Rangoli was done in small patterns — 2 feet square — but now entire floor areas of rooms and hotel foyers are covered in intricate detailed designs. Traditionally, such floor decorations were done only on auspicious occasions or festivals. But today, any occasion is good enough — weddings, birthday parties, opening ceremonies, etc. In the deep South and South West of India and Kerala, flowers are used to create floor art.
In Indian cultures, all guests and visitors occupy a very special place, and a rangoli is an expression of this warm hospitality. In particular, the Hindu Diwali festival is widely celebrated with rangoli, since at this time, people visit each other's homes to exchange greetings and sweets.
The motifs in traditional Rangoli are usually taken from Nature - peacocks, swans, mango, flowers, creepers, etc. The colors traditionally were derived from natural dyes - from barks of trees, leaves, indigo, etc. However, today, synthetic dyes are used in a range of bright colors. The materials used for Rangoli take on either a flat appearance, when a uniform monolayer of powders are sprinkled or a 3-D effect when different sized grains like cereals, pulses etc are used either in their natural coloring or tinted with natural dyes are used.
Source : http://en.wikipedia.org/wiki/Rangoli
See Some Fabulous Diwali Rangoli Patterns, Kolam Rangolis, Kolam Patterns, Rangoli Photos As Following: