What is the GIF file format?
The .gif file format, short for Graphics Interchange Format, is used in raster graphics. Files contain a lossless bitmap image and gained high popularity on the Internet - historically only JPEG was more widely used. The format was developed by CompuServe (credited to Steve Wilhite) and first deployed in 1987 as GIF87a. The 1989 revision, GIF89a, added support for animation, transparency and comment extensions, and is the version used by virtually all modern .gif files today.
How is the GIF format used?
GIF is often used on the Internet because it provides wide support and can be easily transferred between different platforms and applications. It is specifically popular for displaying short looping clips, because this format may include not only singular images but also sequences of images. Therefore many .gif files are used to depict uncomplicated animations. The format is also used on websites to display small graphics such as navigation buttons or header images. For richer animation with full colour depth, formats such as WebP or APNG are now common alternatives.
Restrictions of the GIF format
GIF graphic is useful for presenting images characterised by a not-too-complicated structure, because it has certain restrictions. The format supports up to 8 bits per pixel, so a single .gif image may be comprised of up to 256 different colours from a 24-bit RGB palette. In animated GIFs each frame also supports only a 256-colour palette, making the format unsuitable for photographic content where millions of colours are needed.
Additional information
.gifimages are compressed with the Lempel-Ziv-Welch (LZW) lossless method of data compression, which reduces the file size without interfering with the quality of the image.- The format supports transparent pixels; however, there is a restriction - they must be either completely transparent or completely opaque, so semi-transparent (alpha-blended) pixels are impossible.
- Looping behaviour in animated GIFs is controlled by a
NETSCAPE2.0application extension block embedded in the file.
Security & safety
RISK: LOWGIF is image data with no scripting, so opening one is safe in any viewer. Two historical caveats: malformed GIFs have occasionally triggered image-decoder vulnerabilities, so keep your viewer/OS updated; and animated GIFs with rapid flashing can be a problem for photosensitive users. There is no macro/executable risk in the format itself.
Format details
in a nutshellPrograms that open GIF files
Windows4 apps
GIMP
Open-source Open as layers (each frame = a layer) to edit, then File -> Export As to re-save as GIF, PNG, WebP, etc. 
IrfanView
Free Open the .gif to view frames and animation; Save As to export to PNG/JPG/WebP or extract frames. 
Windows Photos
Built-in Double-click to open in Photos; it displays GIFs (animation playback supported in current builds). 
Web browser (Chrome, Edge, Firefox)
Free Drag the .gif into a browser tab, or double-click - animated GIFs play and loop automatically. 
macOS2 apps
Preview
Built-in Double-click to open in Preview; it shows each GIF frame and can export to PNG/JPG. 
Linux2 apps
ezgif.com
Free Upload to view, crop, resize, optimize, or convert the GIF to MP4/WebP/PNG entirely in the browser. Technical details
deep spec| MIME type | image/gif |
| Magic bytes | "GIF87a" or "GIF89a" at byte offset 0 (6-byte signature and version string) |
| Color depth | Up to 8 bits per pixel; maximum 256 colors per frame |
| Compression | LZW (Lempel-Ziv-Welch) lossless |
| Animation | Multi-frame sequences with per-frame delay timing and configurable loop count |
| Transparency | Binary index transparency only - no partial alpha channel; each pixel is fully opaque or fully transparent |
| Color tables | Optional global color table plus per-frame local color table, each holding up to 256 palette entries |
| Maximum canvas size | 65,535 x 65,535 pixels |
| Frame disposal modes | 4 defined methods: keep in place, restore to background color, restore to previous content, unspecified |
| Interlacing | Optional 4-pass interlaced rendering mode for progressive display |
| Byte order | Little-endian |
| Extension block types | Graphic Control Extension, Comment Extension, Plain Text Extension, Application Extension (e.g. NETSCAPE2.0 for looping) |
| Released | 1987 (GIF87a); GIF89a (animation, transparency) in 1989 |
| Open standard | Yes · royalty-free |
| Specification | www.w3.org |
GIF conversions
Community Q&A
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