If was an American science fiction magazine launched in March 1952 by Quinn Publications, owned by James L. Quinn. The magazine was moderately successful, though it was never regarded as one of the first rank of science fiction magazines. It achieved its greatest success under editor Frederik Pohl, winning the Hugo Award for best professional magazine three years running from 1966 to 1968. If was merged into Galaxy Science Fiction after the December 1974 issue, its 175th issue overall.
Source: IF Magazine : Free Texts : Download & Streaming : Internet Archive