Technology

Greedy algorithm A greedy algorithm builds a solution step-by-step by choosing the best immediate option. Useful when local choices lead to a global optimum or a provable approximation; widely used…

Green Revolution Mid-20th century transformation in crop production driven by high-yield seeds, irrigation, fertilizers and modern farming practices, which greatly increased food supplies and spark…

Grid computing: distributed resource sharing for large-scale computation Grid computing Grid computing coordinates heterogeneous, networked computers to solve large problems by sharing resources, middleware, and services; widely used in science, engineering, and data…

Guillotine: design, history, and cultural significance Guillotine A comprehensive overview of the guillotine — the mechanized execution device associated with late 18th‑century France — covering its design, origins, use, controversies and legacy.

Guitar Hero II (2006) Guitar Hero II Guitar Hero II, the 2006 sequel to Guitar Hero, expanded the console rhythm-game formula with new songs, cooperative play and an influential guitar-shaped controller, helping popul…

Gyrocompass — Non‑magnetic navigation instrument Gyrocompass A gyrocompass is a navigation instrument that finds true (geographic) north using a fast-spinning rotor and Earth’s rotation rather than magnetism; widely used at sea and in inerti…

Hacker (computer expert and intruder) Hacker A hacker is a person skilled with computers who explores systems, programs, or networks. The term spans ethical security research, creative tinkering, and illegal intrusion; distin…

Hacksaw: hand and powered saw for cutting metal and plastic Hacksaw A hacksaw is a sawing tool, hand or powered, used mainly for cutting metal, plastic and similar materials. It has a frame, removable blade and variable tooth pitch for different ma…

Haiku (operating system) Haiku is an open-source desktop operating system that reimplements and extends ideas from BeOS, focusing on responsiveness, simplicity, and a modern C++-based architecture under th…

Hair clipper A hair clipper is a handheld tool for cutting hair close to the scalp; this article explains its parts, operation, types, history, maintenance and common uses.

Hair dryer (blow dryer) Hair dryer Portable electrical appliance that produces a directed stream of hot or cool air to accelerate drying and styling of hair. Describes parts, operation, history, uses, and common var…

Hammer: types, parts, history, uses and safety Hammer Comprehensive overview of the hammer: its structure, common types (claw, ball-peen, sledge), historical development, uses in construction and metalwork, and basic safety and care t…

Handheld Game Console Portable, self-contained gaming devices with built-in screen, controls and battery for playing video games away from a TV or PC; overview, features, history and modern trends.

Hanja: Chinese characters used in Korean writing Hanja Hanja are Chinese characters borrowed into Korean. This article explains their features, history, readings, modern role in South and North Korea, education, and distinctions from H…

Haptic technology (haptics) Haptic technology Haptic technology provides tactile and force feedback to simulate touch and physical interaction. It is used across consumer devices, gaming, VR/AR, medicine and robotics to improv…

Hard Disk (Hard Disk Drive): Overview, Design, Capacity, Uses Hard disk Encyclopedic overview of hard disk drives (HDDs): magnetic storage principles, main components, capacity units (byte, MB, GB, TB), common uses, performance traits and differences f…

Hardware (physical components and devices) Hardware Physical components and devices used in machinery and electronics, including mechanical fittings, electronic circuits, and computer parts; types, history, manufacturing, uses, and…

Harrow (agricultural implement) Harrow (tool) A harrow is a soil-working implement used to break up clods, smooth the seedbed, control weeds and cover seed; it complements ploughing and predates modern mechanized tillage.

Hash table (data structure) Hash table A hash table maps keys to buckets using a hash function for fast lookup, insert and delete. Covers structure, collision resolution, complexity, tuning and common applications.

Hatchet: the one-handed axe used for chopping and campcraft Hatchet A hatchet is a small, one-handed axe used for splitting wood, carving, and general outdoor or domestic tasks. It has deep prehistoric roots and modern forms remain common in campin…

hCard (HTML vCard): a microformat for publishing contact information hCard hCard is a microformat that maps vCard data to HTML class names so people, organization and place contact details can be embedded in web pages and read by software.

HD DVD (High-Definition DVD) HD DVD HD DVD was an early high-definition optical disc format developed as a successor to DVD. It lost the commercial format war to Blu-ray in 2008 and is now discontinued, but influence…

Headphones — personal audio listening devices Headphones Overview of headphones: types, components, history, uses and safety. Explains designs (over-ear, in-ear, wireless), common connectors, and precautions to protect hearing.

Headset: definition, components, history, and common uses Headset A headset combines headphones and a microphone into a single worn device. This article explains types, parts, connectivity, uses (telephony, gaming, broadcasting), and practical di…

Health regeneration in video games Health regeneration (video games) Health regeneration is a game mechanic that restores a character’s life over time after taking damage. This article explains types, history, design trade-offs, and notable examples…

Hearing aid: overview, types, components and uses Hearing aid A hearing aid is a small electronic device worn in or behind the ear to amplify sound for people with hearing loss. This article explains design, types, history, fitting and how th…

Heat pump A heat pump is a device that transfers thermal energy from a colder source to a warmer space. It uses refrigeration principles to heat, cool, or provide hot water and is widely use…

Heat sink — passive and active devices for thermal management Heat sink A heat sink is a component that transfers and dissipates heat from hot parts (like CPUs or power devices) into the surrounding medium. Designs balance materials, surface area, airf…

HelenOS — microkernel multiserver operating system from Charles University HelenOS HelenOS is an open-source microkernel-based OS developed at Charles University for research and teaching; it emphasizes modular, multiserver design and portability across processor…

Helping hand (third hand) — adjustable jig for soldering and fine work Helping hand A helping hand (third hand) is a small, adjustable jig used to hold parts steady during soldering, modelmaking, jewelry work and other precision tasks. It improves accuracy and saf…

Herman Hollerith: Pioneer of Mechanical Data Processing Herman Hollerith Biography and significance of Herman Hollerith, inventor of punched-card tabulation, his machines, business, and influence on modern data processing and early computing.

Heterojunction bipolar transistor (HBT) Heterojunction bipolar transistor A transistor variant that uses different semiconductor materials at the emitter–base junction to improve speed, efficiency and high-frequency performance; widely used in RF and hig…

Hex editor — binary and raw-data editor Hex editor A hex editor displays and edits files or devices at the byte level, showing hexadecimal values and text; used for debugging, reverse engineering, forensics, and repairing binary da…

High fidelity (hi‑fi): overview, components, history and listening culture High fidelity High fidelity (hi‑fi) describes audio reproduction that aims to faithfully reproduce original sound. Covers components, technical criteria, history, listening practices, and how en…

High-Definition Multimedia Interface (HDMI) High-Definition Multimedia Interface HDMI is a single-cable digital interface that carries uncompressed video, multi-channel audio, and control signals between consumer and professional AV devices.

High-level programming language An overview of high-level programming languages: definition, key characteristics, history, common uses and how they differ from low-level languages.

High-pass filter: principles, types, and practical uses High-pass filter An overview of high-pass filters—circuits and algorithms that pass signals above a cutoff frequency—covering characteristics, common designs, applications, and design trade-offs.

Eighth generation of video game consoles: history and impact History of video game consoles (eighth generation) Overview of the eighth generation (beginning c.2012): major home consoles, handhelds, market forces, technical and commercial trends, and the transition toward hybrid and streaming…

Fifth generation video game consoles (1993–2003) History of video game consoles (fifth generation) Overview of the fifth generation (32/64‑bit) consoles: key home systems, handhelds, technical innovations (3D, CD‑ROM), market outcomes, notable games and long‑term legacy includin…

Fourth generation video game consoles (16-bit era) History of video game consoles (fourth generation) Overview of the fourth generation (16-bit) consoles: key systems, technical advances, major franchises, handhelds like the Game Boy, market dynamics, and legacy leading into the 32…

Second-generation video game consoles (1976–1984) History of video game consoles (second generation) Survey of the second generation of home video game consoles (circa 1976–1984): key systems, technical traits, market dynamics, and its lasting influence on the industry.

Sixth generation of video game consoles: Dreamcast, PlayStation 2, GameCube, Xbox History of video game consoles (sixth generation) Overview of the sixth generation of home video game consoles: timeline, major systems (Dreamcast, PS2, GameCube, Xbox), technical innovations, market outcomes and lasting influence…

Third generation of video game consoles (the 8‑bit era and the NES revival) History of video game consoles (third generation) The third generation (mid‑1980s) saw the rise of 8‑bit home consoles, the market recovery led by Nintendo's Famicom/NES, new technical standards and business practices, and the shi…

Hitbox (video games) Hit box (video games) An explanation of hitboxes in video games: definitions, types (hurtbox, hitbox, splash), technical implementation, gameplay effects, history, and common issues like lag and friendl…

Holography: principles, history, techniques and applications Holography Holography records and reconstructs three-dimensional images by capturing interference patterns of coherent light; used in art, security, microscopy, metrology and data storage.

Household appliances Home appliance Devices designed for everyday domestic tasks—cooking, cleaning, food storage and more—ranging from large built‑in machines to portable gadgets. Overview, categories, history, uses,…

Home computer Domestic personal computers of the late 20th century: affordable machines designed for use with a television or monitor for gaming, learning, programming and household tasks.

Honda Civic Compact car produced by Honda since 1972, known for economy, durability, and a wide range of body styles and performance variants across multiple generations.