This represents the Yin/Yang symbol, especially when one half of the circle is shaded black and the other half is white (with the white half half having a black dot in it, and the black half having a white dot.
Superman gone gay? LOL
Ceiling pull switch on an electrical diagram--see link
It is the symbol for Alcoholics Anonymous.
a cirlce with a v inside it means that its a volt meter
A c inside a circle means "with" in medical terms.
Compass Rose
Usually, "Go this way."
It's the symbol for anarchy.
Compass Rose
Equality.
I believe a circle within a circle is not part of Braille - Braille consists of a series of dots arranged in patterns.
It symbolise the cartographer's visual resource' sizes.
a target maybe?... or a bull's eye?