1. Technology (Level 1)
2. Applied science
3. Appropriate technology
4. Emerging technologies
5. Innovation
6. Invention (Level 4)
7. Maintenance
8. Miniaturization
9. Problem solving
10. Research and development
11. Scientific instrument
12. Simulation
13. Technological convergence
14. Technological determinism
15. Technology adoption life cycle
16. Technology and society
17. Technology assessment
18. Technology life cycle
19. Technology transfer

This section contains 65 articles.

1. Engineering (Level 2)
2. Nanotechnology (Level 4)
   1. Molecular machine
3. Nuclear technology (Level 4)
4. Technical drawing (Level 4)
5. Engineering ethics
6. Risk management
7. Engineering management
8. Engineering design process
   1. Requirements analysis
   2. Feasibility study
9. Computer-aided design
10. Engineering economics
11. Reverse engineering

This section contains 51 articles.

1. Agricultural engineering
2. Applied mechanics
3. Biological engineering
   1. Biochemical engineering
   2. Biomedical engineering (Level 4)
   3. Pharmaceutical engineering
4. Ceramic engineering
5. Chemical engineering (Level 4)
   1. Chemical reaction engineering
   2. Nuclear engineering
   3. Molecular engineering
   4. Petroleum engineering
   5. Process engineering
   6. Polymer engineering
6. Civil engineering (Level 3)
   1. Architectural engineering (Level 4)
   2. Construction engineering
      1. Demolition
   3. Earthquake engineering
   4. Environmental engineering
   5. Geotechnical engineering
      1. Directional drilling
   6. Hydraulic engineering
   7. Mining engineering
   8. Structural engineering
   9. Transportation engineering
   10. Highway engineering
7. Electrical engineering (Level 4)
   1. Computer engineering
8. Energy engineering
   1. Power engineering
   2. Telecommunications engineering
   3. Electronic engineering
   4. Control engineering
   5. Radio-frequency engineering
9. Engineering physics
10. Industrial engineering (Level 4)
    1. Computer-aided engineering
    2. Manufacturing engineering
11. Mechanical engineering (Level 3)
    1. Aerospace engineering (Level 4)
    2. Mechatronics
    3. Railway engineering
    4. Marine engineering
    5. Automotive engineering
12. Military engineering (Level 4)
13. Sanitary engineering
14. Security engineering
15. Software engineering (Level 4)
16. Structural analysis
17. Systems engineering

1. Arable land
2. Crop (Level 4)
   1. Cash crop
   2. Nonfood crop
   3. Fiber crop
3. Agricultural machinery
4. Agricultural cycle
   1. Growing season
   2. Season extension
5. Agricultural land
6. Pasture

1. Agricultural science (Level 4)
2. Agricultural chemistry
3. Agricultural economics
4. Agricultural philosophy
5. Agricultural soil science
6. Agroecology
7. Agricultural policy
8. Agricultural geography
9. Agricultural education
   1. Agricultural extension
10. Agrometeorology

• Also see Agricultural engineering in the Engineering section

1. Beekeeping (Level 4)
2. Dairy (Level 4)
   1. Dairy farming
3. Dryland farming
4. Desert farming
5. Rainfed agriculture
6. Extensive farming
7. Gardening (Level 4)
8. Intensive farming (Level 4)
9. Mechanised agriculture
10. Orchard (Level 4)
11. Organic farming (Level 4)
12. Genetically modified crops
13. Sustainable agriculture (Level 4)
14. Permaculture
15. Subsistence agriculture (Level 4)
16. Urban agriculture
17. Pastoralism
18. Plantation
19. Shifting cultivation
20. Regenerative agriculture
21. Intensive animal farming
22. Free range
23. Hydroponics
24. Sericulture
25. Viticulture
26. Fungiculture
27. Olericulture
28. Slash-and-burn agriculture
29. Vertical farming
30. Polyculture
    1. Multiple cropping
    2. Intercropping

This section contains 8 articles.

1. Aquaculture (Level 4)
2. Mariculture
3. Algaculture
4. Fish farming
5. Freshwater prawn farming
6. Integrated multi-trophic aquaculture
7. Marine shrimp farming
8. Seaweed farming

1. Aerial application
2. Acaricide
3. Agrochemical
4. Agent Orange
5. Aldrin
6. Chemosterilant
7. DDT
8. Defoliant
9. Fumigation
10. Fungicide
11. Herbicide
12. Insecticide
13. Lindane
14. Malathion
15. Methoxychlor
16. Pest (organism)
17. Pest control
    1. Biological pest control
    2. Integrated pest management
18. Pesticide (Level 4)
19. Rodenticide
20. Scarecrow
21. Soil steam sterilization
22. Tetraethyl pyrophosphate
23. Toxaphene

1. Apiary
2. Barn (Level 4)
3. Farm (Level 4)
4. Fish hatchery
5. Granary (Level 4)
6. Grain elevator
7. Greenhouse
8. Orangery
9. Paddy field
10. Pavilion
11. Plant nursery
12. Raised field
    1. Chinampa
    2. Waru Waru
13. Seedbed
14. Shed
15. Silo (Level 4)
16. Stable (Level 4)
17. Terrace (earthworks)
18. Ranch

This section contains 9 articles.

1. Garden (Level 3)
2. Arboretum
3. Botanical garden
4. Chinese garden
5. English landscape garden
6. French formal garden
7. Japanese garden
8. Persian gardens
9. Spanish garden

1. Animal husbandry (Level 3)
2. Animal slaughter
3. Breed (Level 4)
4. Culling
5. Domestication (Level 3)
6. Goat farming
7. Horseshoe
8. Animal feed
   1. Fodder
      1. Hay (Level 4)
      2. Straw
   2. Forage
   3. Fish meal
9. Livestock (Level 4)
10. Pig farming
11. Poultry farming
12. Selective breeding (Level 4)
    1. Animal breeding
    2. Purebred
13. Sheep farming
14. Slaughterhouse
15. Antibiotic use in livestock

This section contains 4 articles.

1. Agronomy (Level 4)
2. Plant breeding (Level 4)
   1. Cultivar (Level 4)
3. Crop yield

This section contains 8 articles.

1. Harvest (Level 4)
   1. Threshing
   2. Winnowing
2. Irrigation (Level 4)
3. Tillage (Level 4)
4. Silage
5. Sowing
6. Postharvest

This section contains 17 articles. See "Pedology" in Earth Science

1. Nutrient management
2. Beneficial organism
3. Cover crop
4. Crop rotation
5. Fertilizer (Level 3)
   1. Compost
   2. Vermicompost
   3. Green manure
   4. Guano
   5. Manure
6. Mulch
   1. Plastic mulch
7. Nitrogen fixation
8. Norfolk four-course system
9. No-till farming
10. Three-field system
11. Soil salinity control

1. Horticulture (Level 4)
2. Espalier
3. Floriculture
4. Grafting
5. Layering (horticulture)
6. Plant propagation
7. Pollarding
8. Pollination management
9. Pruning
10. Smudge pot
11. Topiary
12. Transplanting
13. Basal shoot
14. Pomology
15. Companion planting
16. Genetically modified tree
17. Indigenous horticulture
18. Urban horticulture
19. Hardiness (plants)
    1. Hardiness zone
20. Drought tolerance
21. Tropical horticulture

1. Fishery
2. Fishing line
   1. Dropline
   2. Longline fishing
3. Fishing net
   1. Gillnetting
   2. Seine fishing
4. Fishing rod
   1. Fish hook
   2. Fishing lure
   3. Fishing reel
   4. Fishing float
5. Fish trap
   1. Crab trap
   2. Fishing weir
   3. Lobster trap
6. Trapping
   1. Bait

1. Agroforestry
2. Arboriculture
3. Logging
4. Silviculture
5. Coppicing
6. Controlled burn

1. Community-supported agriculture
   1. Teikei
2. Corporate farming
3. Family farm
4. Agricultural cooperative
5. Agribusiness
6. Agricultural marketing
7. Sharecropping
8. Tenant farmer

This section contains 8 articles.

1. Working animal
2. Draft horse
3. Guide dog
4. Ox
5. Pack animal
6. Police dog
7. Service animal
8. Sled dog

1. Environmental impact of agriculture
2. Agricultural expansion
3. Agricultural pollution

1. Biotechnology (Level 3)
2. Cell culture
   1. Plant tissue culture
3. Genetic engineering (Level 3)
4. Recombinant DNA
   1. Genetically modified organism (Level 4)
   2. CRISPR
   3. Molecular cloning
5. Cloning (Level 4)
   1. Somatic cell nuclear transfer
6. Gel electrophoresis (Level 4)
7. Polymerase chain reaction (Level 4)
8. Western blot
9. Cyborg
10. Whole genome sequencing
11. Tissue engineering
12. Biochip
13. De-extinction
14. Genome editing
15. Nuclear transfer
16. Pharming (genetics)
17. Biomimetics
18. DNA microarray
19. Micropropagation
20. Biological hazard
21. Bioterrorism
22. Pharmacogenomics
23. Biopharmaceutical
24. Genetic testing
25. Synthetic biopolymer
26. Biomaterial
27. Agricultural biotechnology
28. Environmental biotechnology
29. Bioreactor
30. Gene therapy
31. Stem-cell therapy
32. Antisense therapy
33. Organ printing
34. Protein engineering
35. Anaerobic digestion
36. Bioleaching
37. Biomining
38. Somatic fusion
39. Synthetic biology

1. Computing (Level 4)
2. Information technology (Level 4)
3. Abacus (Level 4)
4. Calculator (Level 4)
5. Slide rule
6. Data (computer science) (Level 4)
   1. Data communication (Level 4)
   2. Metadata
7. File sharing
8. Human–computer interaction
9. Informatics
10. Open source

1. Computer science (Level 3)
2. Artificial intelligence (Level 3)
3. Computer architecture (Level 4)
4. Computer simulation (Level 4)
5. Parallel computing (Level 4)
   1. General-purpose computing on graphics processing units
6. Augmented reality
7. Virtual reality
8. Concurrent computing
   1. Monitor (synchronization)
9. Floating-point arithmetic
10. Real-time computing
11. Computer graphics (computer science)
    1. Color management
    2. Transform, clipping, and lighting

1. Cache (computing)
2. Cache coherence
3. Distributed computing
   1. Computer cluster
   2. Grid computing
4. Cloud computing
5. Optical computing
6. Quantum computing
7. Von Neumann architecture
8. 8-bit computing
9. 16-bit computing
10. 32-bit computing
11. 64-bit computing
12. Endianness
13. Multithreading (computer architecture)
14. Multiprocessing
15. Instruction set architecture
    1. x86
       1. x86-64
    2. ARM architecture family
    3. IBM POWER architecture
    4. MIPS architecture
    5. Very long instruction word
16. System time
    1. Epoch (computing)
    2. Unix time

1. Computer security (Level 4)
2. Firewall (computing)
3. Transport Layer Security
4. Security bug
   1. Zero-day vulnerability
5. Denial-of-service attack
   1. Botnet
6. Copy protection
   1. Digital rights management
7. Malware (Level 4)
   1. Computer virus
   2. Computer worm
   3. Trojan horse (computing)
   4. Ransomware
   5. Spyware
8. Authentication (Level 4)
   1. Password
   2. Security token
   3. Multi-factor authentication
   4. User (computing)
9. Security through obscurity
   1. Obfuscation (software)
   2. Steganography

This section contains 17 articles.

1. Cryptography (Level 3)
2. Blockchain
3. Block cipher
4. Brute-force attack
5. Caesar cipher
6. Cipher
7. Cryptanalysis
8. Cryptogram
9. Digital signature
10. Encryption (Level 4)
11. Enigma machine
12. Key (cryptography)
13. One-time pad
14. Public-key cryptography
    1. Diffie–Hellman key exchange
    2. RSA cryptosystem
15. Symmetric-key algorithm

1. Computer hardware (Level 4)
2. Computer (Level 2)
3. Booting
   1. BIOS
      1. UEFI
   2. Reboot
4. Processor (computing)
   1. Central processing unit (Level 4)
      1. Microprocessor
         1. Multi-core processor
   2. Coprocessor
5. Motherboard
6. Processor register
7. Floating-point unit
8. Graphics processing unit
9. Arithmetic logic unit
10. Digital signal processor
11. Bus (computing)
    1. SATA
    2. Parallel ATA
    3. Industry Standard Architecture
    4. Peripheral Component Interconnect
    5. PCI Express
    6. Front-side bus
12. Expansion card
    1. Sound card
    2. Graphics card
    3. PC Card
    4. ExpressCard
13. Modem
14. Device driver
15. Intel High Definition Audio
16. Moore's law
17. Clock rate
18. Embedded system
19. Real-time clock
20. Computer cooling
21. Analog computer
22. Stored-program computer
23. Hardware acceleration
24. Plug and play
25. Input/output
    1. Input device
    2. Output device

This section contains 14 articles.

1. IBM PC compatible
2. Mainframe computer
3. Microcomputer
4. Mobile device (Level 4)
   1. Smartphone (Level 4)
   2. Tablet computer
   3. Smartwatch
5. Personal computer (Level 4)
   1. Desktop computer
   2. Gaming computer
   3. Home computer
   4. Laptop
6. Supercomputer (Level 4)
7. Workstation

This section contains 24 articles.

1. User interface (Level 4)
2. Graphical user interface
   1. Window (computing)
   2. X Window System
3. Command-line interface
4. Computer keyboard (Level 4)
5. Computer monitor (Level 4)
6. Cut, copy, and paste
7. Virtual reality headset
8. Computer port (hardware)
   1. IEEE 1394
   2. USB
      1. USB-C
   3. D-subminiature
   4. Digital Visual Interface
   5. DisplayPort
   6. HDMI
   7. VGA connector
   8. Thunderbolt (interface)
9. Pointing device
   1. Computer mouse (Level 4)
   2. Touchpad
   3. Touchscreen (Level 4)
10. Webcam

1. Software (Level 4)
2. Application software
3. Chatbot
4. Computer program (Level 4)
5. Database (Level 4)
   1. Data mining
   2. Big data
6. Emulator
7. Media player software
8. Mobile app
9. Open-source software (Level 4)
10. Spreadsheet (Level 4)
11. System software
12. Web application
    1. Webmail
    2. Web content management system
13. Web browser (Level 4)
14. Word processor (Level 4)
15. Desktop publishing
16. Plug-in (computing)
17. POSIX
18. GNU Project
19. Input method

This section contains 17 articles.

1. Firmware
2. Operating system (Level 4)
   1. Real-time operating system
3. Virtual machine
4. Kernel (operating system)
5. Job (computing)
6. Task (computing)
7. Thrashing (computer science)
8. Thread (computing)
9. Preemption (computing)
10. Process (computing)
11. Computer multitasking
12. Scheduling (computing)
13. System call
14. Time-sharing
15. Working set
16. Mobile operating system

For units of information (bit, byte, megabyte, etc.), see Physical sciences/Basics and measurement

1. Computer file (Level 4)
2. Backup
3. Barcode (Level 4)
   1. QR code
4. File system (Level 4)
   1. HFS Plus
   2. File Allocation Table
   3. NTFS
   4. ext4
   5. ISO 9660
   6. Universal Disk Format
5. Directory (computing)
6. Filename extension
7. Data storage (Level 4)
   1. Computer data storage
   2. Cloud storage
8. RAID
9. Disk partitioning
10. Computer memory
11. Binary file
12. Text file
    1. Formatted text
    2. Plain text

This section contains 18 articles.

1. File format
2. Archive file
   1. ZIP (file format)
   2. 7z
3. Document file format
   1. PDF
4. Image file format
   1. GIF
   2. JPEG
   3. TIFF
   4. PNG
   5. SVG
5. Audio coding format
   1. MP3
6. Video coding format
7. Container format
   1. MPEG-4
   2. Ogg

This section contains 5 articles.

1. Volatile memory
2. Random-access memory (Level 4)
   1. Dynamic random-access memory
   2. Static random-access memory
3. Virtual memory

This section contains 22 articles.

1. Non-volatile memory
2. Read-only memory (Level 4)
3. Magnetic storage
   1. Floppy disk
   2. Hard disk drive (Level 4)
   3. Magnetic tape (Level 4)
      1. Magnetic-tape data storage
      2. VHS
      3. Videotape
4. Flash memory
   1. USB flash drive
   2. Solid-state drive
   3. Memory card (Level 4)
      1. CompactFlash
      2. SD card
      3. MultiMediaCard
      4. Universal Flash Storage
5. Optical disc (Level 4)
   1. Compact disc
   2. DVD
   3. LaserDisc
   4. Blu-ray

1. Computer network (Level 4)
   1. Intranet
2. Email (Level 4)
   1. Internet Message Access Protocol
   2. Simple Mail Transfer Protocol
   3. Spamming
3. Bluetooth
4. Cellular network
   1. GSM
5. Client–server model
6. Content delivery network
7. Ethernet (Level 4)
8. Information system
9. Network interface controller
10. Network packet
11. Network topology
12. Network switch
13. Node (networking)
14. Internet of things
15. Private network
16. Reverse proxy
17. Router (computing) (Level 4)
18. Routing
19. Server (computing)
    1. Proxy server
    2. Web server
20. Subnet
21. Tunneling protocol
22. Wireless network
    1. Wi-Fi (Level 4)
    2. Wireless mesh network

This section contains 42 articles. For Internet culture, see Society and social sciences/Culture#Internet medium

1. Internet (Level 3)
2. ARPANET
3. Communication protocol
4. Common Gateway Interface
5. Domain name
6. File Transfer Protocol
7. Hashtag
8. HTTP (Level 4)
   1. HTTPS
9. Hyperlink
10. Instant messaging
    1. Online chat
    2. IRC
11. Internet protocol suite (Level 4)
    1. Internet Protocol
    2. IP address
    3. IPv4
    4. IPv6
    5. Transmission Control Protocol
12. Internet service provider
13. Peer-to-peer
    1. BitTorrent
    2. Napster
14. Social media (Level 4)
    1. Blog
    2. Bulletin board system
    3. Chat room
    4. Internet forum
    5. Online dating
    6. Social networking service
    7. Usenet
15. Web 2.0
16. Search engine (Level 4)
17. Tor (network)
18. URL
19. Website (Level 4)
    1. Home page
    2. Web page
    3. Wiki
20. World Wide Web (Level 4)
    1. Dark web
    2. Deep web

This section contains 2 articles.

1. Amazon Web Services
2. Google Cloud Platform

This section contains 5 articles.

1. Flickr
2. Netflix
3. Pornhub
4. Steam (service)
5. YouTube (Level 4)

This section contains 2 articles.

1. Craigslist
2. Taobao

This section contains 3 articles.

1. MSN
2. Naver
3. Yahoo

This section contains 6 articles.

1. GitHub
2. Google Maps
3. Internet Archive
4. IMDb
5. Rotten Tomatoes
6. Wikipedia (Level 4)

This section contains 1 article.

1. Berkeley Open Infrastructure for Network Computing

This section contains 2 articles.

1. Google Search
2. Microsoft Bing

This section contains 27 articles.

1. 2channel
2. 4chan
3. Blogger (service)
4. DeviantArt
5. Discord
6. Facebook (Level 4)
7. ICQ
8. Instagram
9. Line (software)
10. LinkedIn
11. Myspace
12. Pinterest
13. Reddit
14. Slack (software)
15. Skype
16. Snapchat
17. Telegram (software)
18. Tencent QQ
19. TikTok
20. Tinder (app)
21. Tumblr
22. Twitch (service)
23. Twitter
24. Weibo
25. VK (service)
26. WeChat
27. WhatsApp

This section contains 63 articles.

1. Software development
2. Software prototyping
3. Reusability
4. Software portability
5. Transparency (human–computer interaction)
6. Library (computing)
7. Formal specification
8. Formal verification
9. Software design
10. Abstraction (computer science)
11. Variable (computer science)
12. Function (computer programming)
13. Pointer (computer programming)
14. Recursion (computer science)
15. Iteration
16. Computer programming (Level 4)
17. Flowchart
18. Source code
19. Bytecode
20. Object code
21. Executable
22. Parameter (computer programming)
23. Collation
24. Universal Product Code
25. Character encoding (Level 4)
    1. ASCII
    2. Mojibake
    3. Unicode
       1. UTF-8
26. Error correction code
27. Compiler (Level 4)
28. Interpreter (computing)
29. Control flow
30. Macro (computer science)
31. Regular expression
32. Calling convention
33. Programming language (Level 4)
34. Programming paradigm (Level 4)
    1. Functional programming (Level 4)
    2. Structured programming (Level 4)
    3. Modular programming
    4. Object-oriented programming (Level 4)
    5. Declarative programming
    6. Imperative programming
    7. Logic programming
35. API
    1. Carbon (API)
    2. Cocoa (API)
    3. Open Database Connectivity
    4. Windows API
       1. DirectX
          1. Direct3D
    5. OpenGL
    6. Vulkan
36. Software testing
37. Software bug
38. Debugging
39. Application checkpointing
40. Exception handling
41. Version control
42. Patch (computing)
43. Software maintenance
44. Software documentation

This section contains 43 articles.

1. Syntax (programming languages)
2. Metasyntax
3. Backus–Naur form
4. Type conversion
5. Data type
6. Delimiter
7. Operator overloading
8. Language binding
9. Low-level programming language
   1. Machine code
   2. Assembly language (Level 4)
10. High-level programming language
    1. C (programming language) (Level 4)
    2. C++
    3. C Sharp (programming language)
    4. Objective-C
    5. Haskell
    6. Java (programming language) (Level 4)
    7. Kotlin (programming language)
    8. Lisp (programming language)
    9. Lua
    10. Scala (programming language)
    11. Swift (programming language)
    12. Visual Basic (.NET)
11. Shading language
12. R (programming language)

This section contains 1 article.

1. SQL

This section contains 3 articles.

1. HTML (Level 4)
   1. HTML5
2. XML

This section contains 6 articles.

1. Python (programming language)
2. Ruby (programming language)
3. PHP
4. Perl
5. JavaScript (Level 4)
6. Shell script

This section contains 6 articles.

1. ALGOL
2. BASIC
3. Pascal (programming language)
4. Fortran
5. Ada (programming language)
6. COBOL

This section contains 1 article.

1. CSS

This section contains 19 articles.

1. AI alignment
2. Artificial general intelligence
3. Artificial intelligence visual art
4. Neural network (machine learning)
5. Computer chess
6. Computer Go
7. Computer vision
8. Existential risk from artificial intelligence
9. Generative artificial intelligence
10. Large language model (Level 4)
11. Machine learning
    1. Deep learning
12. Natural language processing
    1. Speech recognition
    2. Machine translation
13. Philosophy of artificial intelligence
14. Technological singularity
15. Turing test
16. Weak artificial intelligence

See also video game hardware section under games for early Home Computers

1. Amazon Kindle
2. Amiga
3. Arduino
4. Chromebook
5. Commodore 64
6. Deep Blue (chess computer)
7. iPad
8. iPhone (Level 4)
9. iPod
10. Mac (computer) (Level 4)
    1. iMac
11. PC-98
12. Raspberry Pi
13. Samsung Galaxy
14. Walkman
15. ZX Spectrum

This section contains 18 articles.

1. Analytical engine
2. Antikythera mechanism
3. Atanasoff–Berry computer
4. Atlas (computer)
5. Colossus computer
6. Difference engine
7. EDSAC
8. EDVAC
9. ENIAC (Level 4)
10. IBM Personal Computer
11. IBM 7030 Stretch
12. Manchester computers
13. Harvard Mark I
14. TRS-80
15. UNIVAC I
16. Whirlwind I
17. Z3 (computer)
18. Apple II

This section contains 2 articles.

1. AlphaGo
2. ChatGPT

This section contains 5 articles.

1. Firefox
2. Google Chrome
3. Internet Explorer
4. Microsoft Edge
5. Safari (web browser)

This section contains 2 articles.

1. Gmail
2. Microsoft Outlook

This section contains 1 article.

1. Visual Studio

This section contains 10 articles.

1. Adobe Creative Suite
   1. Adobe Flash
   2. Adobe Photoshop
2. Auto-Tune
3. GarageBand
4. GIMP
5. Inkscape
6. iTunes
7. Microsoft Paint
8. VLC media player

This section contains 11 articles.

1. Adobe Acrobat
2. Emacs
3. LibreOffice
4. Microsoft Office
   1. Microsoft Excel
   2. Microsoft PowerPoint
   3. Microsoft Word
5. MySQL
6. TeX
7. WinRAR
8. Vim (text editor)

This section contains 20 articles.

1. Android (operating system) (Level 4)
2. iOS
3. DOS
   1. MS-DOS (Level 4)
4. Mac operating systems
   1. Classic Mac OS
   2. macOS
5. Microsoft Windows (Level 4)
   1. Windows 3.1
   2. Windows 9x
   3. Windows NT
      1. Windows XP
      2. Windows 7
      3. Windows 10
      4. Windows 11
6. Symbian
7. Unix (Level 4)
8. Unix-like
   1. Linux (Level 4)
      1. Debian

This section contains 2 articles.

1. AutoCAD
2. MATLAB

This section contains 3 articles.

1. GDK
2. KDE
3. Wine (software)

This section contains 3 articles.

1. Java virtual machine
2. VirtualBox
3. VMware

This section contains 9 articles.

1. Electronics (Level 3)
   1. Analogue electronics
   2. Digital electronics
2. Circuit design (Level 4)
   1. Electronic design automation
   2. Printed circuit board (Level 4)
   3. SPICE
3. Electronic circuit
   1. Multimeter

This section contains 36 articles.

1. Electronic component
2. Amplifier (Level 4)
   1. Operational amplifier
   2. Vacuum tube (Level 4)
3. Capacitor (Level 4)
   1. Ceramic capacitor
   2. Electrolytic capacitor
   3. Film capacitor
   4. Leyden jar
   5. Supercapacitor
   6. Variable capacitor
4. Diode (Level 4)
   1. Light-emitting diode (Level 4)
5. Electrical connector (Level 4)
6. Inductor (Level 4)
7. Power supply (Level 4)
   1. Current source
   2. Voltage source
8. Resistor (Level 4)
   1. Potentiometer
9. Switch (Level 4)
   1. Knife switch
   2. Relay (Level 4)
   3. Rotary switch
10. Transducer
    1. Actuator
       1. Solenoid
    2. Sensor (Level 4)
       1. Avalanche photodiode
       2. Photodiode
       3. Photomultiplier tube
       4. Phototube
       5. Stretch sensor
       6. Thermistor
       7. Thermocouple
11. Transformer (Level 4)

This section contains 3 articles.

1. Consumer electronics (Level 4)
2. AC adapter
3. Remote control (Level 4)

This section contains 16 articles.

1. Asynchronous circuit
2. Logic gate
   1. AND gate
   2. Digital buffer
   3. Inverter (logic gate)
   4. NAND gate
   5. NOR gate
   6. OR gate
   7. XOR gate
   8. XNOR gate
3. Adder (electronics)
   1. Binary multiplier
   2. Subtractor
4. Flip-flop (electronics)
5. Synchronous circuit
   1. Clock ___domain crossing

This section contains 14 articles.

1. Bridge circuit
   1. Wheatstone bridge
2. Electronic oscillator
   1. Clock generator
      1. Clock signal
   2. Crystal oscillator
   3. Variable-frequency oscillator
3. Frequency mixer
4. Gyrator
5. Negative impedance converter
6. Power inverter
7. Rectifier
   1. Diode bridge
8. Voltage regulator

This section contains 14 articles.

1. Semiconductor device (Level 4)
2. Integrated circuit (Level 3)
   1. Application-specific integrated circuit
   2. Charge-coupled device (Level 4)
   3. Field-programmable gate array
   4. System on a chip
      1. Network on a chip
   5. Very-large-scale integration
3. Transistor (Level 4)
   1. Bipolar junction transistor
   2. Field-effect transistor
      1. MOSFET
   3. Transistor–transistor logic
   4. CMOS

This section contains 17 articles.

1. Signal processing (Level 4)
   1. Digital signal
2. Analog-to-digital converter
3. Digital-to-analog converter
4. Filter (signal processing) (Level 4)
   1. All-pass filter
      1. Lattice phase equaliser
   2. Band-pass filter
   3. Mechanical filter
   4. High-pass filter
   5. Low-pass filter
5. Multiplexing
6. Noise (electronics)
   1. Signal-to-noise ratio (Level 4)
7. Oscilloscope (Level 4)
8. Sampling (signal processing)
   1. Nyquist–Shannon sampling theorem

This section contains 7 articles.

1. Antenna (radio) (Level 4)
   1. Antenna array
2. Electromagnetic shielding
   1. Faraday cage
3. Transmission line
   1. Coaxial cable
   2. Waveguide (Level 4)

This section contains 5 articles.

1. Energy development
   1. Electrification
2. Propellant
3. Renewable energy (Level 3)
4. Sustainable energy

This section contains 25 articles.

1. Fuel (Level 4)
2. Biofuel (Level 4)
   1. Biomass (energy)
   2. Charcoal (Level 4)
3. Fossil fuel (Level 3)
   1. Coal (Level 3)
   2. Coke (fuel)
   3. Fracking
   4. Natural gas (Level 3)
      1. Liquefied natural gas
      2. Liquefied petroleum gas
   5. Oil well (Level 4)
      1. Petroleum reservoir
      2. Oil platform
4. Hydrogen economy
5. Oil refinery (Level 4)
   1. Aviation fuel
      1. Jet fuel
   2. Diesel fuel
   3. Fuel oil
   4. Gasoline (Level 4)
   5. Kerosene (Level 4)
   6. Liquid fuel
6. Nuclear fuel
   1. Nuclear fuel cycle

This section contains 15 articles.

1. Heating, ventilation, and air conditioning (Level 4)
   1. Chimney (Level 4)
   2. Fireplace (Level 4)
   3. Heat pump
2. Air conditioning (Level 4)
   1. Evaporative cooler
   2. Passive cooling
   3. Windcatcher
3. Boiler
4. Central heating (Level 4)
5. Fan (machine)
   1. Ceiling fan
6. Heat exchanger
7. Refrigeration (Level 3)
   1. Yakhchāl

This section contains 13 articles.

1. Candle (Level 4)
2. Electric light (Level 3)
   1. Flashlight
   2. Fluorescent lamp
   3. Incandescent light bulb (Level 4)
   4. Neon lighting
3. Gas lighting
   1. Gas mantle
4. Lantern
5. Match
6. Oil lamp
7. Prism lighting
   1. Light tube

This section contains 41 articles.

1. Power station (Level 4)
   1. Electric generator (Level 4)
      1. Induction generator
   2. Electricity generation (Level 4)
2. Hydropower (Level 3)
   1. Hydroelectricity (Level 4)
   2. Tidal power
   3. Watermill (Level 4)
3. Microgeneration
   1. Micro-CHP
4. Nuclear power (Level 3)
   1. Fusion power
      1. Inertial confinement fusion
      2. Tokamak
   2. Nuclear reactor
      1. Breeder reactor
      2. Molten-salt reactor
      3. Heavy water reactor
      4. Small modular reactor
      5. Nuclear marine propulsion
      6. Nuclear meltdown
5. Solar energy (Level 3)
   1. Solar power (Level 4)
   2. Solar cell (Level 4)
      1. Solar panel
6. Thermal power station
   1. Boiler (power generation)
   2. Cogeneration
   3. Combined cycle power plant
   4. Concentrated solar power
   5. Cooling tower (Level 4)
   6. Fossil fuel power station
      1. Coal-fired power station
      2. Gas-fired power plant
   7. Geothermal power (Level 4)
7. Turbine (Level 4)
   1. Gas turbine (Level 4)
   2. Steam turbine (Level 4)
   3. Wind turbine (Level 4)
8. Wind power (Level 3)
   1. Windmill (Level 4)