The definition of Anal Ring, closely resembles the actual words which is describing. The Anal Ring is the skin that is between the outer side and the inner side of the anus. It is just the circular gateway of your buttock.
The Anal Ring can be open and closed, by means of contraction and relaxation of the sphincter. A rounded-shaped muscle which encircles the Anal Ring.
To a girl, exploring her Anal Ring can be close to as orgasmic as finding her G-Spot, also known as "Grafenberg spot"