Fanac is a fan slang

Fanspeak

Fanspeak is the slang or jargon current in science fiction and fantasy fandom, especially those terms in use among readers and writers of science fiction fanzines....

 term (from fannish activities) for activities within the realm of science fiction fandom

Science fiction fandom

Science fiction fandom or SF fandom is a community or "fandom" of people actively interested in science fiction and fantasy and in contact with one another based upon that interest...

, and occasionally used in media fandom

Media fandom

Media fandom refers to the collective fandoms focused on contemporary television shows and movies. Media fandom has a focus on relationships and is distinct from science fiction fandom, anime fandom, book fandom, music fandom, soap opera fandom, sports fandom, and video game fandom.-History:Media...

. It may be distinguished from fan labor

Fan labor

Fan labor is a term used to refer to the productive creative activities engaged in by fans, primarily those of various media properties or musical groups...

 in that "fanac" includes the publication of science fiction fanzines of the traditional kind (i.e., not primarily devoted to fan fiction

Fan fiction

Fan fiction is a broadly-defined term for fan labor regarding stories about characters or settings written by fans of the original work, rather than by the original creator...

), and the organization and maintenance of science fiction conventions and science fiction clubs.

"Fanac" has also been used as a title for at least two science fiction fanzines, one published by Terry Carr

Terry Carr

Terry Gene Carr was a U.S. science fiction author, editor, and teacher.Terry Carr was born in Grants Pass, Oregon...

 and Ron Ellik, and later continued by Walter H. Breen

Walter H. Breen

Walter H. Breen was an American author. He is best known among coin collectors for writing Walter Breen's Complete Encyclopedia of U.S. and Colonial Coins. "Breen numbers", from his encyclopedia, are widely used to attribute varieties of coins...

, in the late 1950s through early 1960s; and the other published by Swedish

Sweden

Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

 fan John-Henri Holmberg

John-Henri Holmberg

John-Henri Bertilson Holmberg is a Swedish author, critic, publisher and translator, and a well-known science fiction fan. In the early 1960s he edited Science fiction Forum with Bertil Mårtensson and Mats Linder and published over 200 science fiction fanzines of his own, in addition to his...

from 1963 to 1994.