SDI may refer to: Arts and entertainment SDI (arcade game), 1987, by Sega S.D.I. (video game), 1986, by Cinemaware Companies and organizations Samsung SDI, battery manufacturer Scottish Development International Scuba Diving International SDI Media Group, providing subtitling and language services SDI Presence, US IT consultancy SDI Technologies, a consumer electronics manufacturer, New Jersey, U.S.A. Service Desk Institute, for computer help desk staff Slum Dwellers International (Italian Democratic Socialists), a political party Software Design Inc. Spiritual Directors International, supporting spiritual direction Steel Dynamics, Inc., a steel producer, Indiana, US.A. In science and technology Computing and telecommunications Serial data input in the Serial Peripheral Interface bus Serial digital interface for sending video signals over coaxial cable Single document interface, a style of graphical user interface Software-defined infrastructure, with no human intervention Spatial data infrastructure Standard Disk Interconnect, a DEC standard Statistical Design Institute's SDI Tools for Microsoft Excel System Deployment Image, a Microsoft disk image file format Medicine Sulfadimidine, an antibiotic Other uses in science and technology Selective dissemination of information Silt density index in reverse osmosis systems Smoke-developed index, the concentration of smoke emitted by a material Spiral Dynamics Integral, a model of evolutionary development Stand density index, of the stocking of a stand of trees Subsurface drip irrigation Suction Diesel Injection, a Volkswagen diesel engine Other uses Saidor Airport (IATA code), in Madang Province, Papua New Guinea Socio-Demographic Index of the Global Burden of Disease Study State Disability Insurance of California, US Strategic Defense Initiative, US anti-missile project