The Kinsey scale attempts to describe a person's sexual history or episodes of their sexual activity at a given time. It uses a scale from 0 to 6. "0" means the person tested is exclusively heterosexual. A person scoring "6" is exclusively homosexual. In the "Kinsey Reports", an extra grade was used for asexuality. The scale was first published in "Sexual Behavior in the Human Male" (1948). It was also important in the complementary work "Sexual Behavior in the Human Female" (1953).