kb/data/developer.mozilla.org/en-US/docs/Glossary/Lossy_compression-0.md

title	chunk	source	category	tags	date_saved	instance
Lossy compression - Glossary | MDN	1/3	https://developer.mozilla.org/en-US/docs/Glossary/Lossy_compression	reference	web, html, css, javascript, documentation	2026-05-05T05:37:06.402682+00:00	kb-cron

• Skip to main content
• Skip to search

MDN HTML HTML: Markup language

HTML reference

• Elements
• Global attributes
• Attributes
• See all…

HTML guides

• Responsive images
• HTML cheatsheet
• Date & time formats
• See all…

Markup languages

• SVG
• MathML
• XML

CSS CSS: Styling language

CSS reference

• Properties
• Selectors
• At-rules
• Values
• See all…

CSS guides

• Box model
• Animations
• Flexbox
• Colors
• See all…

Layout cookbook

• Column layouts
• Centering an element
• Card component
• See all…

JavaScriptJS JavaScript: Scripting language

JS reference

• Standard built-in objects
• Expressions & operators
• Statements & declarations
• Functions
• See all…

JS guides

• Control flow & error handing
• Loops and iteration
• Working with objects
• Using classes
• See all…

Web APIs Web APIs: Programming interfaces

Web API reference

• File system API
• Fetch API
• Geolocation API
• HTML DOM API
• Push API
• Service worker API
• See all…

Web API guides

• Using the Web animation API
• Using the Fetch API
• Working with the History API
• Using the Web speech API
• Using web workers

All All web technology

Technologies

• Accessibility
• HTTP
• URI
• Web extensions
• WebAssembly
• WebDriver
• See all…

Topics

• Media
• Performance
• Privacy
• Security
• Progressive web apps

Learn Learn web development

Frontend developer course

• Getting started modules
• Core modules
• MDN Curriculum
• Check out the video course from Scrimba, our partner

Learn HTML

• Structuring content with HTML module

Learn CSS

• CSS styling basics module
• CSS layout module

Learn JavaScript

• Dynamic scripting with JavaScript module

Tools Discover our tools

• Playground

• HTTP Observatory

• Border-image generator

• Border-radius generator

• Box-shadow generator

• Color format converter

• Color mixer

• Shape generator

About Get to know MDN better

• About MDN

• Advertise with us

• Community

• MDN on GitHub

Blog

1. Glossary
2. Lossy compression

Lossy compression

Lossy compression , or irreversible compression, is a data-compression method that uses inexact approximations and partial-data discarding to represent content. In simpler terms: lossy compression causes data from the initial file to be lost, possibly causing degradation in quality. The process of such compression is irreversible; once lossy compression of the content has been performed, the content cannot be restored to its original state. Therefore, content that has undergone lossy compression should generally not be further edited. Lossy compression is widely used in image formats such as JPEG, WebP, and audio and video formats such as MP3, MP4, H.264 and others. Compression methods such as WebP are capable of both lossy and lossless compression depending on the compression level or the options you want to use during encoding. Although there is no obvious difference in quality between the two images above, the size of the second image has been significantly reduced using lossy compression.

In this article

• See also

See also

• Related glossary terms:
  • Lossless compression