Assuming you had read the section on A.M. you would be aware that two of the disadvantages of a.m. transmission are the twice the bandwidth to convey the same information and only 25% of the power is used in each side band. The remaining 50% of power is expended in the carrier.
It makes more sense in terms of economy of bandwidth as well as economy of power to simply transmit only one side band. This is called S.S.B. or Single Side band.