SF

SF is a two-letter abbreviation which may refer to:

In places:
* San Francisco, California, a city with a population of more than 730,000, located on the West Coast of the United States.
** The San Francisco Giants, a franchise in the MLB
** The San Francisco 49ers, a franchise in the NFL
* Sioux Falls, South Dakota, a city with a population of over 140,000, the center of the Midwest.
* Sofia, Bulgaria, the capital city of Bulgaria

In things:
* Speculative fiction, term coined by Robert A. Heinlein as a synonym for science fiction, but now refers to a literary genre which includes science fiction. Also abbreviated "spec-fic," "S-F", or "sf".
* Science Fiction, Literary genre, also abbreviated as "Sci-Fi".
* Scuderia Ferrari, the racing division of the Ferrari automobile company
* Significant figures (in mathematics)
* Spontaneous fission, a nuclear decay route in which a superheavy nucleus splits into two.
* SourceForge, a collaborative software development management system
* Special forces, small, highly trained and specialised military units
* Security Forces, US Air Force's version of MP and ground infantry
* Stade Français Paris, a French rugby union team
* Statsforetak, a type of Norwegian state enterprise
* Six Flags, a chain of theme parks
* "Svensk Filmindustri", the Swedish Film Industry
* Tassili Airlines, IATA airline designator
* Salad Fingers, a flash animation created by David Firth
* Salmon farming, farming of salmon (see Fish farming)
* Selle Français, French breed of horse
* Superleague Formula, a new motor racing formula mixing football (soccer)and motorsports

In acronyms:
* "Socialistisk Folkeparti", the Danish Socialist People's Party.
* Sinn Féin, an Irish political party.
* Schweizer Fernsehen, or Swiss Television, a German-language television network in Switzerland.
* Science fiction, a literary genre

In music:
* Sforzando, musical notation for a sudden, strong emphasis
* Senses Fail a hardcore punk band from New Jersey
* Switchfoot, an alt-rock band
* Scaterd Few, a Christian punk band
* Shadows Fall, a metal band
* Sarcastic Front a hardcore punk band from Czech Republic

In video games:
* Stellar frontier, a game by Stardock in 1997
* Soldier Front, a tactical first-person shooter game, licensed by ijji
* SourceForts, a modification of the Half-Life 2 first-person shooter game
* Street Fighter (series), a series of electronic fighting games by the company Capcom
* Syphon Filter, a series of action-shooter games on the Sony Playstation consoles
* Strategy First, a video game software company
* Star Fox (series), a video game series by Nintendo

In defunct uses:
* Finland as an abbreviation for "Suomi-Finland". "Suomi" is the Finnish-language name for Finland.
* Suomen Filmiteollisuus, a Finnish film production company.
* The Hull classification symbol for a "Fleet Submarine" in the United States Navy

In other:
* Steve Francis, an NBA player for the Houston Rockets
* Small Forward, a basketball position
* Sacrifice fly, baseball terminology