Technology

Representational State Transfer (REST) Representational state transfer An architectural style for networked applications that uses stateless communication, uniform interfaces, and resource representations, widely applied to web APIs and services.

Research and development (R&D): purpose, types, and impact Research and development Overview of research and development: its main types, processes, funding, measurement, policy tools, technology transfer, sector roles, benefits, challenges and emerging trends.

Residual-current device (RCD) — safety device for electric shock and leakage protection Residual-current device A residual-current device (RCD) detects imbalance between live and neutral conductors and rapidly interrupts supply to reduce electric shock, electrocution and fire risk. Types, op…

Resonator: Principles, Types and Applications Resonator A resonator is any object or system that naturally oscillates at particular frequencies. This article explains how resonators work, common types, historical notes, and typical uses…

RGB color model and its uses in digital imaging RGB Overview of the RGB additive color model: how red, green and blue light combine to form colors, historical background, technical characteristics, common uses and important distinct…

Rhapsody (Apple operating system) Rhapsody (operating system) Rhapsody was Apple’s transitional OS after acquiring NeXT: a NeXTSTEP/OpenStep–based platform that introduced Yellow Box (later Cocoa) and Blue Box compatibility, ultimately evolvi…

Rhythm game (rhythm action video games) Rhythm game Overview of rhythm games: gameplay mechanics, controllers, history from PaRappa to Dance Dance Revolution and Guitar Hero, variants, cultural impact, and notable design features.

Robot — programmable machines, types, history and uses Robot An overview of robots: what they are, main components and types, historical and cultural background, practical applications, and distinctions from other automated systems.

Rocketdyne F-1 rocket engine Rocketdyne F-1 The Rocketdyne F-1 was the powerful single-chamber liquid-fueled engine that powered the Saturn V first stage. Developed in the 1950s–60s, it produced roughly 1.5 million lbf thrus…

Roland D-50: 1987 Linear Arithmetic Digital Synthesizer Roland D-50 The Roland D-50 (1987) is a 61‑key digital synthesizer that introduced Linear Arithmetic synthesis—combining sampled attack transients with synthesized sustains—to create the disti…

Romanization of Japanese (rōmaji) Romanization of Japanese Rōmaji is the representation of Japanese using the Latin (Roman) alphabet. This article explains common systems, conventions, history, uses, and limitations of romanizing Japanese.

Rootkit: stealth software for persistent, unauthorized access Rootkit A rootkit is software (often malicious) that hides its presence and maintains secret, persistent control over a computer or device. This article explains types, history, detection,…

Rotary encoder: principles, types, and practical applications Rotary encoder A rotary encoder measures angular position and motion. This article explains how encoders work, compares major types, outlines typical uses in industry and robotics, and highlights…

Rotary switch A mechanical switch operated by rotating a shaft to select among multiple electrical circuits or settings. Used in instrumentation, audio, industrial controls and range selection.

Rotating bolt (firearm locking mechanism) Rotating bolt A rotating bolt is a firearm locking system where the bolt rotates to engage recesses in the receiver or barrel extension, providing strong lock-up used in many bolt-action and mod…

Rotating furnace: spin-casting mirrors and lenses for astronomy Rotating furnace A rotating furnace uses controlled rotation and heat to form large glass optics with parabolic surfaces, enabling efficient production of telescope mirrors and lenses and influenci…

Router (network device) Router A router directs data between computer networks, using hardware and software to forward packets, apply policies, and connect local networks to the Internet.

Rover: meanings, robotic explorers, vehicles and cultural uses Rover Rover denotes a wanderer or mobile machine. Common uses include planetary and lunar exploration rovers, British automobile marques, scouting sections, historic sea rovers, sports r…

RPM Package Manager (RPM) RPM Package Manager RPM is a widely used package format and set of tools for installing, querying, building and verifying software on many Linux distributions. It defines .rpm files, metadata, signatu…

RSA — cryptography, institutions, and other meanings RSA RSA commonly denotes the Rivest–Shamir–Adleman public-key cryptosystem; it also names organisations (RSA Security, the Royal Society for the encouragement of Arts), the Republic of…

Runtime: program execution, environments, and runtime systems Runtime The period and system context in which a program executes. Covers runtime environments, libraries, virtual machines, activities like loading, linking, JIT compilation, and differen…

Rust (programming language): overview, design, history, and uses Rust (programming language) Rust is a systems programming language emphasizing memory safety, concurrency, and performance without a garbage collector. It is used for operating system components, browsers, ne…

S.M.A.R.T. — Self‑Monitoring, Analysis, and Reporting Technology for storage drives S.M.A.R.T. S.M.A.R.T. is a drive‑level monitoring system that tracks indicators of hard drive and SSD health, reports status to software, and helps predict some impending hardware failures.

Safe (container) A safe is a secure, usually metal container for protecting valuables from theft, fire and water. Covers construction, locks, ratings, installation, vaults, standards and guidance f…

Safe mode (computing) Safe mode Safe mode is a minimal startup environment used by operating systems to diagnose and repair problems by loading only essential software and drivers, and sometimes limited networkin…

Safety razor A safety razor is a shaving tool that shields the skin from the blade edge. This article explains its design, history, varieties, technique, and modern relevance for grooming and w…

Samsung Galaxy: overview of Samsung's mobile device family Samsung Galaxy Samsung Galaxy is Samsung Electronics' long-running family of mobile devices, including Android smartphones, tablets and wearables known for varied sizes, features and yearly flags…

Samsung Galaxy Note — stylus-equipped Android smartphones and tablets Samsung Galaxy Note Overview of Samsung's Galaxy Note series: large-screen Android devices with the S Pen, key features, history including the Note7 recall, typical uses, and how the line relates to o…

Samsung Galaxy Note 10 2019 flagship Android phablets from Samsung: the compact Note10 and the larger Note10+, with S Pen, Dynamic AMOLED displays, multi-lens cameras, in-display fingerprint sensor, and…

Samsung Galaxy S7: overview, design, features and legacy Samsung Galaxy S7 A concise encyclopedia entry on the Samsung Galaxy S7, covering its design, hardware, camera, water resistance, variants, software and its place in Samsung's smartphone lineup.

Samsung Galaxy S8 — overview, design, hardware, and legacy Samsung Galaxy S8 The Samsung Galaxy S8 series (S8, S8+, S8 Active) are 2017 flagship Android smartphones by Samsung featuring Infinity Display design, biometric options, IP68 water resistance, and…

San: meanings across languages, places, science, and culture San A compact reference to the many senses of 'San' — as a name, morpheme, acronym, honorific, people, places, technical term, and cultural reference across world languages and discipl…

Sandbox (computer security) Isolated environments that run untrusted or unknown code safely. Sandboxes can be virtual machines, containers, or application-level restraints used for malware analysis, testing,…

Satellaview: Nintendo's satellite broadcast peripheral for the Super Famicom Satellaview Satellaview was a Japan‑only satellite broadcast peripheral for the Super Nintendo (Super Famicom), delivering episodic games, live audio and timed broadcasts via a partnership bet…

Satellite navigation (satnav) and global navigation satellite systems Satellite navigation Satellite navigation uses networks of orbiting satellites and receivers to determine precise position and time. GNSS includes systems such as GPS, GLONASS, Galileo and BeiDou and s…

Saturn V — the Apollo program’s heavy-lift launch vehicle Saturn V Saturn V was NASA’s three‑stage heavy-lift rocket that carried Apollo crews to lunar orbit and launched Skylab. Developed in the 1960s, it remains a milestone of rocket engineering…

SATySFi: a modern typesetting system SATySFi SATySFi is an open-source, functional-style typesetting system focused on precise layout and mathematical typesetting. It offers a typed language, modular extensions, and aims to b…

Saw (tool): types, history, uses and safety Saw A saw is a tool for cutting materials with a toothed edge or abrasive; this article describes common types, history, operation, uses and essential safety practices.

Scalable Vector Graphics (SVG): an overview and practical guide Scalable Vector Graphics SVG is an XML-based vector image format for two-dimensional graphics, supporting resolution-independent rendering, styling, scripting, animation and accessibility across web and pr…

Scanner An overview of scanners: devices that capture or read data from physical sources, including document/image scanners, barcode readers, radio receivers and medical imaging systems —…

Scanning tunneling microscope An instrument that images and manipulates conductive surfaces at atomic scale by measuring electron tunneling. Widely used in surface science, spectroscopy, nanotechnology and atom…

Scientific management (Taylorism): principles, history and legacy Scientific management Scientific management, or Taylorism, is an early 20th-century approach to organizing work that emphasizes measurement, standardization and managerial control; it shaped manufacturi…

Scissors: design, history, and common uses Scissors Handheld shearing tool with two blades that cross; used for cutting paper, cloth, hair, food and many materials. Covers parts, types, history, common uses and handedness.

Screen (display and partition) Screen A screen is either a surface that shows visual content or a physical mesh/partition that filters, protects, or divides. It covers electronic displays, projection surfaces, touch-se…

Screen tearing: causes, prevention, and practical trade-offs Screen tearing Screen tearing is a visual artifact that occurs when a display shows parts of multiple frames simultaneously. This article explains how it happens, how it is prevented, and the com…

Screwdriver — overview, types, parts, history, and uses Screwdriver A screwdriver is a hand or powered tool used to turn screws. This article explains its parts, common tip shapes, historical development, typical uses, safety and maintenance, and n…

Script.NET (S#) — an embedded scripting language for the .NET platform Script.NET Script.NET (S#) is an open-source, JavaScript-like scripting language that embeds into Microsoft .NET applications. It interprets scripts at runtime without producing extra in-memo…

SCSI (Small Computer System Interface) SCSI SCSI is a family of standards for connecting and communicating with computer storage and peripherals. It defines commands, transport layers and device behaviour used in servers, st…