STS is a three-letter abbreviation with multiple meanings, including:
Société de transport de Sherbrooke
Space Transportation System, the official name for the United States' Space Shuttle program
sequence-tagged site, in genomics
Silver thriosulphate or Silver thriosulfate, in chemistry
Scanning tunneling spectroscopy
Satanas, a Filipino-American gang
Science and technology studies (or, sometimes, Science, technology, and society, ST&S)
Synchronous Transport Signal, part of the SONET communications system
Sail Training Ship
Service to Self
Serviciul de Telecomunicaţii Speciale (Romania)
Semipalatinsk Test Site
Sharepoint Team Services, the original name for Windows SharePoint Services.
State transition system
Strathcona-Tweedsmuir School is a private school near Calgary, Alberta
The Station-to-Station protocol, a cryptographic key agreement scheme that provides mutual authentication.
STS Relay, the speech to speech relay service available via 711 in the United States
Supercooled ternary solution, present in Type Ib polar stratospheric clouds (PSCs).
Synergy Teleconferencing System, a computer bulletin board operating system
Self Tying Shoelace, a magic effect
Stepover Toehold Sleeper, a submission hold used in professional wrestling, currently used by John Cena, who calls it the STFU.
School Travel Services A U.K travelling company intended for schools.
Charles M. Schulz - Sonoma County Airport (IATA airport code)
Special Tactics Squad, An America's Army] gaming clan
STS (cyrillic: СТС) - Russian TV channel.
Street Touring Sport - SCCA Autocross class.
Space Tourism Society