TLS may refer to:

Computing

• Transport Layer Security, a cryptographic protocol for secure computer network communication
• Thread level speculation, an optimisation on multiprocessor CPUs
• Thread-local storage, a mechanism for allocating variables in computer science
• Transparent LAN Service, a transparent data link connecting remote Ethernet networks

Media

• Theaterlexikon der Schweiz, an encyclopedia about theatre in Switzerland
• Thesaurus Linguae Sericae, a study of the Chinese language
• The Times Literary Supplement, a British weekly literary review
• Town Life Stuff, one of The Sims 3 Stuff packs

Organisations

• Telstra (ASX code), an Australian telecommunications and media company
• Trans Link Systems B.V., a company delivering the OV-chipkaart system to public-transport operators in the Netherlands.
• Transmitter Location Systems, a US satellite radio interference geolocation company

Education

• The Lindsey School, a secondary school in Cleethorpes, North East Lincolnshire, England
• Tallinn Law School, in Estonia
• Torrey Life Science, a biology organization of the University of Connecticut, US
• Trinity Law School, in Santa Ana, California, US
• Trinity Lutheran School (disambiguation), several schools in the US
• Tulane University Law School, in New Orleans, Louisiana, US

Science, medicine and technology

• Thüringer Landessternwarte Tautenburg, the Karl Schwarzschild Observatory, Germany
• Total least squares, a statistical analysis
• Translesion synthesis, a form of DNA repair
• Transponder landing system, an airplane landing system
• Tumor lysis syndrome, a group of metabolic complications that can occur after treatment of cancer
• Tunable laser spectrometer, an instrument in the Mars rover suite Sample Analysis at Mars
• Two-level system, a quantum system

Other uses

• East Timor (IOC code)
• Toulouse–Blagnac Airport (IATA code)
• Typed Letter Signed, in auctions of autographs