A race condition is a concurrency defect in which a program's result depends on the unpredictable timing or ordering of threads or…
A rack focus is a cinematography technique that shifts sharp focus from one subject to another within a single continuous shot.
A rack server is a server built in a standard 19-inch chassis measured in rack units, designed for dense mounting in data…
Radio spectrum is the range of electromagnetic frequencies from about 3 kHz to 3,000 GHz used for wireless communication, allocated and licensed…
RADIUS is a network security protocol that centrally authenticates, authorizes and accounts for users connecting through Wi-Fi, VPN and switch ports.
RAG (retrieval-augmented generation) feeds a language model relevant passages retrieved from external sources so its answers rest on current, verifiable data.
RAID combines several disks into one logical volume using striping, mirroring or parity to improve server storage speed, capacity or fault tolerance.
RAM, or random-access memory, is the fast volatile working memory that holds the code and data a processor is actively using while…
Randomization in experimentation assigns units to treatment or control by chance, so groups are comparable and outcome differences reflect the change.
Range anxiety is the worry that an electric vehicle will run out of charge before reaching its destination or a working charger.
Rank tracking is the scheduled monitoring of where a website appears in search results for chosen keywords, locations and devices over time.
A ranking factor is any signal a search engine uses to decide the order of results for a query, such as relevance,…
Ransomware is malware that encrypts or steals an organization's data and demands payment for decryption or silence, often after a long manual…
Raster graphics in graphic design are images built from a fixed grid of colored pixels, ideal for photographs but limited when scaled…
RAW in photography is an image file that stores minimally processed sensor data, leaving demosaicing, white balance and tone rendering to later…
RAW video records the sensor's mosaic data with minimal processing, so white balance, ISO rendering and color are decided later in post-production.
Ray tracing in games simulates how light rays bounce through a scene to render realistic reflections, shadows and lighting at a high…
RBAC (role-based access control) grants permissions to roles rather than individual users, so access follows job functions in a manageable way.
RCE, or Remote Code Execution, is a vulnerability class that lets an attacker run arbitrary code on a target system over a…
React Native is a cross-platform framework for building iOS and Android apps in JavaScript or TypeScript that render real native interface components.
Read noise is the random electronic noise added when a camera sensor converts and reads out its signal, limiting shadow detail and…
A read replica is a continuously updated copy of a primary database that serves read-only queries, offloading reporting and read traffic from…
Rec. 2020 is the ITU-R recommendation that defines a very wide color gamut and the core signal parameters for UHD video and…
Rec. 709 is the ITU standard that defines HD video primaries, white point, transfer function and signal coding, the default target for…
Recall in model evaluation is the share of actual positive cases that a model correctly identifies, showing how many relevant items it…
A recommendation algorithm is the system a platform uses to pick which content each viewer sees, deciding much of a creator's reach…
Recovery mode is a separate minimal environment that operating systems boot to repair startup, restore backups or reinstall the system.
Recursion is a programming technique in which a function solves a problem by calling itself on smaller instances until it reaches a…
Recursive DNS is the resolution service that answers a client's DNS query completely by querying root, TLD and authoritative servers and caching…
A red team is an authorized group that emulates real attackers against an organization to test how well its people, processes and…
Redis is an in-memory key-value database system with rich data structures, used for caching, sessions, queues, rate limiting and real-time counters.
Redundancy in server reliability means duplicating critical components so that a single failure does not interrupt the service or lose data.
A reflector in photography lighting is a surface that redirects existing light onto a subject to fill shadows, add warmth or shape…
Refresh rate is how many times per second a display redraws its image, measured in hertz, and it shapes motion clarity, smoothness…
ReFS, the Resilient File System, is a Windows file system built for data integrity, very large volumes and fast virtualization workloads.
Regenerative braking slows an electric vehicle by running its traction motor as a generator, returning part of the kinetic energy to the…
A Regional Internet registry is a nonprofit body that allocates IP addresses and AS numbers in one world region and keeps the…
A registrar is an accredited company that registers domain names with TLD registries on behalf of customers and manages their renewals and…
A registry is the organization that operates a top-level domain, keeping its authoritative database of domain names and publishing the TLD zone…
A regression in software quality is a defect where a feature that worked in an earlier version stops working or degrades after…
Regulatory compliance is how an organization identifies the laws that apply to its technology, meets their obligations and proves it to regulators.
Reinforcement learning is a branch of machine learning in which an agent learns by trial and error to choose actions that maximize…
A relational database stores data in tables of rows and columns linked by keys and queried with SQL, enforcing integrity through constraints…
A release candidate is a software build that is feature complete and believed ready to ship, released for final testing before the…
A release channel is a distribution track, such as stable, beta or nightly, that decides which software builds a user receives and…
Remote assistance in extended reality lets an off-site expert see a worker's live view and guide the task with annotations anchored in…
A rendering engine is the browser component that turns HTML, CSS and images into pixels by parsing, styling, laying out, painting and…
A rendering intent is the rule a color management system follows to convert colors between ICC profiles, above all for out-of-gamut colors.
A reorder point is the stock level at which a new purchase order must be placed so replenishment arrives before inventory runs…
Repetition in design is the deliberate reuse of visual elements such as colors, type styles and shapes to create unity, rhythm and…