Best wishes for Happy Diwali (Deepavali) to every one.
As part of the Diwali celebrations oil lamps are lit and placed every where in the house often in artistic arrangements. The lamp symbolizes the light, the energy, illumination and knowledge ( Elimination of ignorance or darkness).
To learn more about the lamp and the philosophy it symbolizes please see the link below. https://sipractce.wordpress.com/2012/06/14/learning-the-basics-of-hindu-philosophy-from-an-oil-lamp/ This is an essay posted earlier.