What Is a JPG (JPEG) File?
The format almost every photo online is saved in - what it does well, what it quietly costs you, and when to reach for something else.
A JPG (also written JPEG) is a raster image format that stores photographs in a small file by throwing away detail your eye is unlikely to miss - a technique called lossy compression. It is the most widely supported image format in the world, which is why almost every photo online, and nearly every shot from a phone or camera, is a JPG. The trade for that small size: no transparency, visible artefacts around sharp edges and text, and a little quality lost every time you re-save.
JPG and JPEG are the same format. The name comes from the Joint Photographic Experts Group, which published the standard in 1992; the two spellings are a leftover from old systems that limited file extensions to three letters, so .jpeg got shortened to .jpg. Nothing about the file differs between them.
What JPG is good at
Photographs. JPG was designed for continuous-tone images, where colour and brightness change gradually across the frame. Its compression works by discarding fine variations the eye barely registers, so a photo shrinks to a fraction of its raw size with no visible difference. For a gallery, a product catalogue, or any page full of photos it is the right tool, and Compress JPG pushes it smaller still when you need to.
What it is bad at
The same compression that flatters photographs mishandles everything else. Sharp edges, text, and flat blocks of colour come out fuzzy, with faint halos and blocky patterns around the crisp parts - logos, screenshots, line art, diagrams. For those PNG is the right format; our JPG vs PNG guide covers the split, and if you already have a graphic saved as JPG, JPG to PNG converts it (though it cannot undo artefacts already baked in).
JPG also has no transparency. There is no alpha channel in the format, so a JPG is always a solid rectangle - anything that needs a see-through background has to be a PNG or WebP instead.
The re-saving trap
Because JPG is lossy, every time you open a JPG and save it again it is compressed again, and a little more detail is lost. Do that enough times and the artefacts pile up visibly - a problem called generation loss. Keep an original, edit from that, and export a fresh JPG each time rather than re-saving the same file over and over.
JPG vs the newer formats
JPG is old, and newer formats beat it on efficiency: WebP and AVIF produce noticeably smaller files at the same quality, and both support transparency. JPG's advantage is universality - it opens on essentially everything, with no exceptions. When page speed matters and your audience is on modern browsers, JPG to WebP is a quick win; when you need something that will open on a decade-old device, JPG is still the safe default.
FAQ
Is JPG the same as JPEG?
Yes, identical - two spellings of one format, split only by old three-letter extension limits. The file is the same either way.
Does JPG support transparency?
No. JPG has no alpha channel, so it is always a solid rectangle. Use PNG or WebP if you need a transparent background.
Why does my JPG look blocky around text?
Because JPG's lossy compression is built for photos, not sharp edges. Save text, logos, and screenshots as PNG instead.
Does saving a JPG lose quality every time?
Yes - each re-save re-compresses and discards a little more detail. Edit from an original and export a fresh copy rather than re-saving the same file repeatedly.
Is my file uploaded when I convert or compress a JPG here?
No. babapic's tools run in your browser, so the file never leaves your device.