AWG stands for American Wire Gauge. It is a standard that determines the cross section of a wire using a gauge for solid, round electrical wires. It is used by Engineers to determine a wires current carrying capabilities. The higher the AWG number, the thinner or smaller the wire. The thicker a wire the less resistance and thus it can carry more voltage a longer distance.
AWG is determined by figuring out the radius of the wire squared, times pi.