What is JPEG (JPG)? | GenClean Glossary

JPEG (JPG)

JPEG is the standard lossy format for photographs, used since 1992 and readable by effectively every device, browser, and program ever made. JPG and JPEG are the same format - the three-letter version exists only because old Windows systems required three-letter file extensions. It compresses photos to small files but doesn't support transparency.

Where JPEG excels

Photographs and photo-like images with smooth gradients compress to a fraction of their raw size with no visible loss at quality settings around 80-90%. Universal compatibility is its superpower: airline check-in systems, government portals, ancient printers - everything accepts a JPG.

Where it fails

Text, line art, and hard edges develop visible ringing and blockiness because the compression model assumes photographic content. It has no alpha channel, so transparent areas get flattened onto a background color. And each re-save re-compresses: editing and saving the same JPG repeatedly compounds the damage.