• Skip to main content
  • Skip to search
  • Skip to select language
MDN Web Docs
  • References
    • Overview / Web Technology

      Web technology reference for developers

    • HTML

      Structure of content on the web

    • CSS

      Code used to describe document style

    • JavaScript

      General-purpose scripting language

    • HTTP

      Protocol for transmitting web resources

    • Web APIs

      Interfaces for building web applications

    • Web Extensions

      Developing extensions for web browsers

    • Web Technology

      Web technology reference for developers

  • Guides
    • Overview / MDN Learning Area

      Learn web development

    • MDN Learning Area

      Learn web development

    • HTML

      Learn to structure web content with HTML

    • CSS

      Learn to style content using CSS

    • JavaScript

      Learn to run scripts in the browser

    • Accessibility

      Learn to make the web accessible to all

  • Plus
    • Overview

      A customized MDN experience

    • AI Help

      Get real-time assistance and support

    • Updates

      All browser compatibility updates at a glance

    • Documentation

      Learn how to use MDN Plus

    • FAQ

      Frequently asked questions about MDN Plus

  • Curriculum
  • Blog
    • Playground

      Write, test and share your code

    • New
      HTTP Observatory

      Scan a website for free

    • AI Help

      Get real-time assistance and support

  • Log in
  • Sign up for free
  1. Glossary
  2. Instance
    • Français
    • 日本語
    • 한국어
    • 中文 (简体)

In this article

  • See also
  1. Glossary
    1. Abstraction
    2. Accent
    3. Accessibility
    4. Accessibility tree
    5. Accessible description
    6. Accessible name
    7. Adobe Flash
    8. Advance measure
    9. Ajax
    10. Algorithm
    11. Alignment container
    12. Alignment subject
    13. Alpha (alpha channel)
    14. ALPN
    15. API
    16. Apple Safari
    17. Application Context
    18. Argument
    19. ARIA
    20. ARPA
    21. ARPANET
    22. Array
    23. ASCII
    24. Aspect ratio
    25. Asynchronous
    26. ATAG
    27. Attribute
    28. Authentication
    29. Authenticator
    30. Bandwidth
    31. Base64
    32. Baseline
    33. Beacon
    34. Bézier curve
    35. bfcache
    36. BiDi
    37. BigInt
    38. Binding
    39. Bitwise flags
    40. Blink
    41. Block
    42. Block cipher mode of operation
    43. Block-level content
    44. Boolean
    45. Bounding Box
    46. Breadcrumb
    47. Brotli compression
    48. Browser
    49. Browsing context
    50. Buffer
    51. Cache
    52. Cacheable
    53. CalDAV
    54. Call stack
    55. Callback function
    56. Camel case
    57. Canonical order
    58. Canvas
    59. Card sorting
    60. CardDAV
    61. Caret
    62. CDN
    63. Certificate authority
    64. Certified
    65. Challenge-response authentication
    66. Character
    67. Character encoding
    68. Character reference
    69. Character set
    70. Chrome
    71. CIA
    72. Cipher
    73. Cipher suite
    74. Ciphertext
    75. Class
    76. Clickjacking
    77. Closure
    78. CMS
    79. Code point
    80. Code splitting
    81. Code unit
    82. Codec
    83. Color space
    84. Color wheel
    85. Compile
    86. Compile time
    87. Composite operation
    88. Computer Programming
    89. Conditional
    90. Constant
    91. Constructor
    92. Continuous Media
    93. Control flow
    94. Cookie
    95. Copyleft
    96. CORS
    97. CORS-safelisted request header
    98. CORS-safelisted response header
    99. Crawler
    100. Credential
    101. CRLF
    102. Cross Axis
    103. Cross-site scripting (XSS)
    104. CRUD
    105. Cryptanalysis
    106. Cryptographic hash function
    107. Cryptography
    108. CSP
    109. CSRF
    110. CSS
    111. CSS Object Model (CSSOM)
    112. CSS pixel
    113. CSS preprocessor
    114. Cumulative Layout Shift (CLS)
    115. Data structure
    116. Database
    117. Decryption
    118. Deep copy
    119. Delta
    120. Denial of Service
    121. Deno
    122. Descriptor (CSS)
    123. Deserialization
    124. Developer Tools
    125. Digest
    126. Digital certificate
    127. Digital signature
    128. Distributed Denial of Service
    129. DMZ
    130. DNS
    131. Doctype
    132. Document directive
    133. Document environment
    134. DOM (Document Object Model)
    135. Domain
    136. Domain name
    137. Domain sharding
    138. Dominator
    139. DoS attack
    140. DSL
    141. DTLS (Datagram Transport Layer Security)
    142. DTMF (Dual-Tone Multi-Frequency signaling)
    143. Dynamic typing
    144. ECMA
    145. ECMAScript
    146. Effective connection type
    147. Element
    148. Encapsulation
    149. Encryption
    150. Endianness
    151. Engine
    152. Entity
    153. Entity header
    154. Enumerated
    155. eTLD
    156. Event
    157. Exception
    158. EXIF
    159. Expando
    160. Fallback alignment
    161. Falsy
    162. Favicon
    163. Federated identity
    164. Fetch directive
    165. Fetch metadata request header
    166. Fingerprinting
    167. Firefox OS
    168. Firewall
    169. First contentful paint
    170. First CPU idle
    171. First input delay
    172. First Meaningful Paint
    173. First paint
    174. First-class Function
    175. Flex
    176. Flex Container
    177. Flex Item
    178. Flexbox
    179. Flow relative values
    180. Forbidden header name
    181. Forbidden response header name
    182. Fork
    183. Fragmentainer
    184. Frame rate (FPS)
    185. FTP
    186. FTU
    187. Function
    188. Fuzz testing
    189. Gamut
    190. Garbage collection
    191. Gecko
    192. General header
    193. GIF
    194. Git
    195. Global object
    196. Global scope
    197. Global variable
    198. Glyph
    199. Google Chrome
    200. GPL
    201. GPU
    202. Graceful degradation
    203. Grid
    204. Grid Areas
    205. Grid Axis
    206. Grid Cell
    207. Grid Column
    208. Grid container
    209. Grid Lines
    210. Grid Row
    211. Grid Tracks
    212. Gutters
    213. gzip compression
    214. Hash
    215. Head
    216. High-level programming language
    217. HMAC
    218. Hoisting
    219. Host
    220. Hotlink
    221. Houdini
    222. HPKP
    223. HSTS
    224. HTML
    225. HTML5
    226. HTTP
    227. HTTP header
    228. HTTP/2
    229. HTTP/3
    230. HTTPS
    231. HTTPS RR
    232. Hyperlink
    233. Hypertext
    234. IANA
    235. ICANN
    236. ICE
    237. IDE
    238. Idempotent
    239. Identifier
    240. Identity provider (IdP)
    241. IDL
    242. IETF
    243. IIFE
    244. IMAP
    245. Immutable
    246. IndexedDB
    247. Information architecture
    248. Inheritance
    249. Ink overflow
    250. Inline-level content
    251. Input method editor
    252. Inset properties
    253. Instance
    254. Internationalization (i18n)
    255. Internet
    256. Interpolation
    257. Intrinsic size
    258. IP Address
    259. IPv4
    260. IPv6
    261. IRC
    262. ISO
    263. ISP
    264. ITU
    265. Jank
    266. Java
    267. JavaScript
    268. Jitter
    269. JPEG
    270. JSON
    271. JSON type representation
    272. Kebab case
    273. Key
    274. Keyword
    275. Largest contentful paint
    276. Latency
    277. Layout viewport
    278. Lazy load
    279. LGPL
    280. Ligature
    281. Literal
    282. Local scope
    283. Local variable
    284. Locale
    285. Localization
    286. Logical properties
    287. Long task
    288. Loop
    289. Lossless compression
    290. Lossy compression
    291. LTR (Left To Right)
    292. Main Axis
    293. Main thread
    294. Markup
    295. MathML
    296. Media
    297. Media query
    298. Metadata
    299. Method
    300. Microsoft Edge
    301. Microsoft Internet Explorer
    302. Middleware
    303. MIME
    304. MIME type
    305. Minification
    306. MitM
    307. Mixin
    308. Mobile First
    309. Modem
    310. Modularity
    311. Mozilla Firefox
    312. Mutable
    313. MVC
    314. Namespace
    315. NaN
    316. NAT
    317. Native
    318. Navigation directive
    319. Netscape Navigator
    320. Network throttling
    321. NNTP
    322. Node
    323. Node.js
    324. Non-normative
    325. Normative
    326. Null
    327. Nullish value
    328. Number
    329. Object
    330. Object reference
    331. OOP
    332. OpenGL
    333. OpenSSL
    334. Opera Browser
    335. Operand
    336. Operator
    337. Origin
    338. OTA
    339. OWASP
    340. P2P
    341. PAC
    342. Packet
    343. Page load time
    344. Page prediction
    345. Parameter
    346. Parent object
    347. Parse
    348. Parser
    349. Payload body
    350. Payload header
    351. PDF
    352. Perceived performance
    353. Percent-encoding
    354. PHP
    355. Physical properties
    356. Pixel
    357. Placeholder names
    358. Plaintext
    359. Plugin
    360. PNG
    361. Polyfill
    362. Polymorphism
    363. POP3
    364. Port
    365. Prefetch
    366. Preflight request
    367. Prerender
    368. Presto
    369. Primitive
    370. Privileged
    371. Privileged code
    372. Progressive Enhancement
    373. Progressive web apps
    374. Promise
    375. Property
    376. Protocol
    377. Prototype
    378. Prototype-based programming
    379. Proxy server
    380. Pseudo-class
    381. Pseudo-element
    382. Pseudocode
    383. Public-key cryptography
    384. Python
    385. Quality values
    386. Quaternion
    387. QUIC
    388. RAIL
    389. Random Number Generator
    390. Raster image
    391. RDF
    392. Real User Monitoring (RUM)
    393. Recursion
    394. Reflow
    395. Regular expression
    396. Relying party
    397. Render-blocking
    398. Repaint
    399. Replay attack
    400. Repo
    401. Reporting directive
    402. Representation header
    403. Request header
    404. Resource Timing
    405. Response header
    406. Responsive web design
    407. REST
    408. RGB
    409. RIL
    410. Robots.txt
    411. Round Trip Time (RTT)
    412. Router
    413. RSS
    414. Rsync
    415. RTCP (RTP Control Protocol)
    416. RTF
    417. RTL (Right to Left)
    418. RTP (Real-time Transport Protocol) and SRTP (Secure RTP)
    419. RTSP: Real-time streaming protocol
    420. Ruby
    421. Safe
    422. Salt
    423. Same-origin policy
    424. SCM
    425. Scope
    426. Screen reader
    427. Script-supporting element
    428. Scroll boundary
    429. Scroll chaining
    430. Scroll container
    431. SCTP
    432. SDK (Software Development Kit)
    433. SDP
    434. Search engine
    435. Secure Context
    436. Secure Sockets Layer (SSL)
    437. Selector (CSS)
    438. Self-Executing Anonymous Function
    439. Semantics
    440. SEO
    441. Serializable object
    442. Serialization
    443. Server
    444. Server Timing
    445. Session Hijacking
    446. SGML
    447. Shadow tree
    448. Shallow copy
    449. Shim
    450. Signature
    451. SIMD
    452. SISD
    453. Site
    454. Site map
    455. SLD
    456. Sloppy mode
    457. Slug
    458. Smoke Test
    459. SMPTE (Society of Motion Picture and Television Engineers)
    460. SMTP
    461. Snake case
    462. Snap positions
    463. SOAP
    464. SPA (Single-page application)
    465. Specification
    466. Speculative parsing
    467. Speed index
    468. SQL
    469. SQL Injection
    470. SRI
    471. Stacking context
    472. State machine
    473. Statement
    474. Static method
    475. Static typing
    476. Sticky activation
    477. Strict mode
    478. String
    479. Stringifier
    480. STUN
    481. Style origin
    482. Stylesheet
    483. Submit button
    484. SVG
    485. SVN
    486. Symbol
    487. Symmetric-key cryptography
    488. Synchronous
    489. Syntax
    490. Syntax error
    491. Synthetic monitoring
    492. Table grid box
    493. Table Wrapper Box
    494. Tag
    495. TCP
    496. TCP handshake
    497. TCP slow start
    498. Telnet
    499. Texel
    500. The Khronos Group
    501. Thread
    502. Three js
    503. Time to first byte
    504. Time to interactive
    505. TLD
    506. TOFU
    507. Top layer
    508. Transient activation
    509. Transport Layer Security (TLS)
    510. Tree shaking
    511. Trident
    512. Truthy
    513. TTL
    514. TURN
    515. Type
    516. Type coercion
    517. Type conversion
    518. TypeScript
    519. UAAG
    520. UDP (User Datagram Protocol)
    521. UI
    522. Undefined
    523. Unicode
    524. Unix time
    525. URI
    526. URL
    527. URN
    528. Usenet
    529. User agent
    530. UTF-8
    531. UUID
    532. UX
    533. Validator
    534. Value
    535. Variable
    536. Vendor Prefix
    537. Viewport
    538. Visual Viewport
    539. Void element
    540. VoIP
    541. W3C
    542. WAI
    543. WCAG
    544. Web performance
    545. Web server
    546. Web standards
    547. WebAssembly
    548. WebDAV
    549. WebExtensions
    550. WebGL
    551. WebIDL
    552. WebKit
    553. WebM
    554. WebP
    555. WebRTC
    556. WebSockets
    557. WebVTT
    558. WHATWG
    559. Whitespace
    560. WindowProxy
    561. World Wide Web
    562. Wrapper
    563. XForms Deprecated
    564. XHTML
    565. XInclude
    566. XLink
    567. XML
    568. XMLHttpRequest (XHR)
    569. XPath
    570. XQuery
    571. XSLT
    572. Zstandard compression

In this article

  • See also

Instance

An object created by a constructor is an instance of that constructor.

See also

  • Instance on Wikipedia

Help improve MDN

Learn how to contribute.

This page was last modified on Jun 8, 2023 by MDN contributors.

View this page on GitHub • Report a problem with this content
MDN logo

Your blueprint for a better internet.

  • MDN on Mastodon
  • MDN on X (formerly Twitter)
  • MDN on GitHub
  • MDN Blog RSS Feed

MDN

  • About
  • Blog
  • Careers
  • Advertise with us

Support

  • Product help
  • Report an issue

Our communities

  • MDN Community
  • MDN Forum
  • MDN Chat

Developers

  • Web Technologies
  • Learn Web Development
  • MDN Plus
  • Hacks Blog
Mozilla logo
  • Website Privacy Notice
  • Cookies
  • Legal
  • Community Participation Guidelines

Visit Mozilla Corporation’s not-for-profit parent, the Mozilla Foundation.
Portions of this content are ©1998–2024 by individual mozilla.org contributors. Content available under a Creative Commons license.