PALETTE
256 colours at most
Each pixel is an 8-bit number pointing into a colour table of 2 to 256 entries. Photos get dithered, which is why they can look grainy.
Pick a formatThe GIF is older than the web browser.
CompuServe published the first version in May 1987. Its palette of up to 256 colours, lossless LZW compression and simple animation still make it the loop people reach for, even where newer formats do the job better.
- Up to 256 colours
- Lossless LZW squeeze
- Frames with delays
- A tiny format with a long life
THE SHORT ANSWER
A palette, a squeeze
and a stack of frames.
Three ideas explain almost everything about GIF.
They also explain its limits.
HISTORY
Born at CompuServe
Version 87a arrived in May 1987 and 89a in July 1989. Its LZW compression is lossless, and later sparked a long patent row.
The patent story
TODAY
Video often wins
In one web.dev example a 3.7 MB GIF became a 341 KB WebM video. MDN suggests WebP, AVIF or APNG for animation.
See the numbers
FOUR THINGS TO TRY
Keep the loop,
lose the weight.
If you publish animations on a website, these steps follow web.dev and MDN guidance. For a reaction in a chat, a GIF is still perfectly fine.
Check the file size first
Animated GIFs can be several megabytes. Look at the size before you put one on a page.
Convert long clips to video
Make WebM and MP4 versions and list both as sources, as web.dev recommends.
Use the looping attributes
web.dev's markup uses autoplay, loop, muted and playsinline so the video behaves like a GIF.
Use PNG for stills
For a still logo or diagram, MDN suggests PNG rather than GIF.
TWO NUMBERS WORTH KNOWING
One limit,
one weigh-in.
The palette size set by the 1989 specification,
and what happens when a GIF becomes a video.
256 colours
Most entries in a colour table
The GIF89a specification indexes colour table entries from 0 to 255, three bytes each. MDN notes dithering is used to simulate more colours.
PALETTE · GIF89a SPEC
341 KB vs 3.7 MB
One animation, as a WebM video
In web.dev's example, a 3.7 MB GIF became a 551 KB MP4 and a 341 KB WebM, with the same looping animation.
FILE SIZE · WEB.DEV
File sizes vary with the clip. The web.dev figures come from one worked example, not a general rule.
A QUICK FORMAT CHECK
Is GIF the right
tool for this?
Pick what you are making to see how well GIF suits it and what reference guides suggest instead. The bar shows how good a fit GIF is.
Based on MDN's image file type guide and web.dev's advice on replacing GIFs with video.
PATENTS AND PRONUNCIATION
Two arguments
that outlived the dial-up era.
GIF's LZW compression was patented. The Library of Congress notes the format became notorious in 1994, when Unisys began charging fees to license LZW. The US patent expired in June 2003, and the European and Japanese patents in June 2004.
Then there is the name. The Library of Congress records that the format's creators said it with a soft g, as in George, while many people use a hard g to match the word graphics. Both are widely heard.
In conversation
Questions people ask
When was the GIF invented?
CompuServe introduced it in 1987. The GIF89a specification lists version 87a as May 1987 and version 89a as July 1989.
Why do GIFs have so few colours?
Each pixel is an 8-bit index into a colour table, and a table has at most 256 entries. To suggest more colours, images are usually dithered.
Is GIF compression lossy?
No. GIF uses LZW, a lossless method. The quality loss people notice usually comes from reducing an image to 256 colours or fewer.
How is GIF pronounced?
The Library of Congress notes the creators used a soft g, like the start of George. Many people say it with a hard g, matching graphics.
Why do websites turn GIFs into videos?
Video files are often much smaller. In a web.dev example, a 3.7 MB GIF became a 341 KB WebM video playing the same loop.
Sources
Each figure on this page comes from the sources below.