The Nebula Awards annually recognize the best works of science fiction or fantasy published in the United States during the previous year. The awards are organized and awarded by the Science Fiction and Fantasy Writers of America (SFWA), a nonprofit association of professional science fiction and fantasy writers. They were first given in 1966 at a ceremony created for the awards, and are given in four categories for different lengths of literary works. A fifth category for film and television episode scripts was given 1974–78 and 2000–09. The rules governing the Nebula Awards have changed several times during the awards' history, most recently in 2010.