Technology

Scythe: traditional mowing and reaping implement Scythe A scythe is a hand tool with a long curved blade used to cut grass or grain. This article covers its design, history, traditional uses, maintenance and cultural significance.

Search algorithm A search algorithm is a procedure for locating data in a structure or space. This article surveys common techniques, their requirements, performance trade-offs, and typical applica…

Secret sharing: threshold schemes, variants, and practical uses Secret sharing Secret sharing divides a secret into parts so only an authorized subset can reconstruct it. Covers threshold schemes, Shamir and Blakley methods, security properties, and real-worl…

Secure Copy (SCP): Encrypted file transfer using SSH Secure copy Secure Copy (SCP) is a simple command-line method for encrypted file transfer over SSH. This article explains how it works, common usage, history, security considerations, and alte…

Secure Digital (SD) card: overview, types, speeds and compatibility Secure Digital card Comprehensive introduction to Secure Digital (SD) memory cards: physical design, SDSC/SDHC/SDXC and microSD families, speed classes and UHS, file systems, compatibility and common…

Sega CD (Mega‑CD): CD-ROM Add‑On for the Sega Genesis Sega CD A compact overview of the Sega CD (Mega‑CD), Sega's CD-ROM add-on for the Genesis: hardware features, history, notable games, reception and legacy.

Sega Genesis (Mega Drive): 16‑bit home console and its legacy Sega Genesis The Sega Genesis (Mega Drive) is Sega's 16-bit home console released in 1988–89. Known for Sonic, arcade ports and bold marketing, it shaped 1990s gaming and helped prompt industry…

Sega Saturn The Sega Saturn is Sega’s 32-bit home video game console released in 1994–95. Noted for dual processors, strong arcade-style 2D ports, and a complex architecture that shaped its co…

Self-driving car A vehicle capable of navigating and performing driving tasks without continuous human input, using sensors, software and maps; used in testing, fleet shuttles and driver-assist fea…

Selfie — definition, history, types, and cultural impact Selfie A selfie is a self-taken photograph, most often made with a phone. This article explains its definition, history, common types, cultural role, technological effects, and notable de…

Semi-automatic Devices or mechanisms that combine automatic cycling of some functions with required human input for others; commonly used of firearms, transmissions and household machines.

Semi-automatic firearm A firearm that uses energy from each fired cartridge to cycle the action and chamber the next round, producing one shot per trigger pull; used in pistols, rifles and shotguns for m…

Semi-automatic shotgun A shotgun that uses recoil or gas to cycle and chamber the next round automatically after each trigger pull. Common in military, law enforcement, hunting and sport shooting for rap…

Sensor: devices that detect and report physical quantities Sensor Overview of sensors: what they measure, how they work, main types, history, common applications, key performance metrics and distinctions between sensor families.

Serial ATA (SATA): interface for connecting hard drives and optical drives Serial ATA Serial ATA (SATA) is a widely used interface standard for connecting storage devices—hard drives, SSDs and optical drives—to a computer. It evolved from PATA and coexists with newe…

Serial Attached SCSI (SAS): architecture, compatibility and uses Serial Attached SCSI Serial Attached SCSI (SAS) is a high-performance serial interface for connecting enterprise storage devices. It evolved from parallel SCSI and emphasizes speed, scalability, and re…

Serial number (unique identifier) Serial number A serial number is a unique identifier assigned to individual items in a sequence. This article explains its purpose, formats, history, common uses, and how it differs from other i…

Serial port (computer interface) Serial port A serial port is a hardware interface for bit‑serial data transfer (often RS‑232/UART). It has been widely used for modems, terminals and embedded equipment and remains common in i…

Serial Storage Architecture (SSA): overview, design, history and legacy Serial Storage Architecture Serial Storage Architecture (SSA) is IBM's 1990s serial block-storage interconnect using ring topology and dual-path redundancy; it was later supplanted by Fibre Channel and SAS.

Serpent (cipher): conservative AES finalist block cipher Serpent (cipher) Serpent is a 128-bit block symmetric-key cipher, an AES finalist known for a conservative design, high parallelism through bit-slicing, three key sizes, and public-domain status fo…

Session key (cryptography) Session key A session key is a temporary symmetric key used to protect the confidentiality and integrity of data for a single communication session. This article explains purpose, generation,…

Sewing machine: history, parts, types, and uses Sewing machine Overview of sewing machines: what they are, main components, historical development, household and industrial types, common stitches and applications, and notable distinctions.

Sex toy Devices and accessories designed to enhance sexual pleasure, used alone or with partners; overview of types, history, uses, safety, and social aspects.

Sexbot: robots designed for sexual and intimate interaction Sexbot Sexbots are machines intended for sexual use and companionship. This article explains what they are, how they are being developed, uses, technical features, ethical concerns, and l…

Shakey the Robot: pioneer of mobile AI and automated planning Shakey the robot Shakey was an early general-purpose mobile robot developed at SRI (1966–1972). It combined perception, reasoning and action and inspired modern AI planning, robotics and computer v…

Shared secret (cryptography): definition, uses, and security Shared secret A shared secret is data known only to communicating parties. This article explains how shared secrets are created, their roles in authentication and key derivation, security concer…

Shareware — software distribution and trial licensing Shareware Shareware is a distribution model that provides free trial copies or limited-feature versions of software so users can evaluate before buying. Covers types, history, uses, and dist…

Sharpie (permanent marker brand) Sharpie Sharpie is a well-known line of permanent markers made by Newell Brands, recognized for many tip styles and quick-drying, long-lasting inks used in art, labeling, and industry.

Shift key (keyboard modifier) Shift key Modifier key used to produce uppercase letters and alternate symbols, used in selection, shortcuts and accessibility. Originated with typewriters; variants include Shift Lock and C…

Shotgun: design, ammunition, types, history and uses Shotgun Comprehensive introduction to shotguns: how they work, main parts, common action types, ammunition (shot and slugs), historical development, uses in sport, hunting and policing, an…

Shovel: design, types, uses and care Shovel An overview of the shovel — a hand tool for scooping and moving loose materials — its parts, common variants, historical development, typical uses and guidance on selection and mai…

Shutter: architecture, optics, organ, and film Shutter A shutter is a movable barrier that controls the passage of light, air, or sound. Common in windows, cameras, projectors, stage lighting, and pipe organs; also the title of several…

Shutter (photography) Device that controls the time light reaches the sensor or film, shaping exposure and motion capture; includes mechanical and electronic types, leaf and focal-plane designs, and pro…

Shuttle (weaving tool): types, history and function Shuttle A shuttle is a hand or machine tool that carries weft yarn through the warp shed to form woven cloth; types, construction, history and modern variations explained.

Sickle (curved agricultural hand tool) Sickle A sickle is a short-handled, curved blade used historically and today to cut grain and grasses. This article explains its design, history, agricultural uses, cultural roles and com…

Side effect (computer science) An explanation of side effects in programming: what they are, common kinds, how languages treat them, why they matter for reasoning, testing and concurrency, and practical examples…

Side-scrolling video game A side-scrolling video game is a 2D game in which the viewpoint follows a character or action across a horizontal plane; commonly used in platformers, shooters and beat 'em ups.

Silicon controlled rectifier (SCR): structure, operation, and applications Silicon controlled rectifier A silicon controlled rectifier (SCR) is a four-layer semiconductor switch used to control large currents and convert AC to DC. This article explains its structure, operation, histo…

Silly Putty — origins, properties, uses, and cultural impact Silly Putty Silly Putty is a silicone-based novelty polymer known for viscoelastic behaviour, accidental mid-20th-century discovery during rubber research, household uses, and a lasting place…

SIM card: function, types, history, and practical considerations SIM card Overview of SIM cards: what they are, how they work, form factors (mini/micro/nano/eSIM), security features, uses, history and current trends like embedded SIM and IoT applications…

SIMATIC — Siemens industrial automation system and PLC family SIMATIC SIMATIC is Siemens' family of industrial automation products, including PLCs, HMIs, I/O and engineering software used to automate manufacturing, process and motion-control systems…

Simulation: concepts, methods, history, and applications Simulation An accessible overview of simulation: what it is, main types and components, historical development, typical uses and examples, and strengths and limitations of simulated models.

Simulation video game A simulation video game models real-world systems or activities, from city-building and flight to social life, varying in fidelity from arcade-like to highly realistic for training…

Simultaneous multithreading (SMT): overview, operation, history and uses Simultaneous multithreading Simultaneous multithreading (SMT) is a CPU architecture technique that allows a superscalar core to issue instructions from multiple threads in the same cycle to improve utilizatio…

Single Event Upset (SEU): causes, effects, and mitigation Single event upset Overview of single event upsets (SEUs): what they are, how energetic particles or interference induce transient errors in microelectronic devices, examples, distinctions, testing a…

Single-player video game A video game intended for one person to play alone, featuring AI opponents or companions, narrative focus, and design choices that shape replayability, pacing, and player experienc…

Siren (noisemaker) A siren is an acoustic warning device—mechanical or electronic—that produces loud, attention‑getting sounds used for emergency vehicles, civil alerts, industrial alarms and signall…

Siri: Apple’s Voice-Based Virtual Assistant Siri Overview of Siri, Apple’s voice-activated assistant: core capabilities, history, platform support, uses, privacy considerations, and comparisons with other digital assistants.