Inverted Yin and Yang Symbol with black representing yin and white representing yang.
The symbol is a visual depiction of the intertwined duality of all things in nature, a common theme in Taoism. 
It is believed to be derived from the 11th century Tiandi Zhiran Hetu (Heaven and Earth’s Natural Diagram of the River), Hetu (Diagram of River), Luoshu (Chart of Luo), Xiantian tu (Diagram of Preceding Heaven) and Taijitu (太極圖) (Diagram of the Great Ultimate).
In its conventional orientation, the hot, bright, white yang nature rises while the cold, dark, black yin nature descends. Taoist esoterics often invert the symbol because they believe in this configuration the heat from the yang will be able to cook the jing in the yin producing qi which leads toward longer life and immortality.

Here the diagram is shown against a feather edged grey background to ensure clarity when displayed over black or white.
Own work
This vector image was created with Inkscape by Klem, and then manually edited by Mnmazur