Hand sweating is a normal function of the body under certain circumstances. Excessive hand sweating is sweating that goes beyond the normal physiological needs of the body. This is Hyperhidrosis.
The palms of the hands are not a typical place for the body to sweat from. If a person is sweating from his or her palms under normal conditions (non-active, no stress or excitement, normal temperature, social interaction) then they may have hyperhidrosis. Hyperhidrosis is a genetically inherited condition. It causes social and functional problems in everyday life.
For additional information on sweaty palms: