What is a JPG file?
JPG, or JPEG after the Joint Photographic Experts Group that designed it in 1992, is the standard format for photographs. It uses lossy compression: it throws away fine detail the eye is unlikely to notice, which lets it shrink a photo to a tenth of its raw size. Cameras, phones, websites, and every piece of software support it, which is why it remains the safe default for sharing pictures more than thirty years later.
Quality settings and generation loss
JPG quality runs from 1 to 100. Around 90 the compression is invisible; 75 to 85 is the sweet spot for web use; below 60 blocky artifacts appear around edges. Every time a JPG is edited and saved again it loses a little more, so keep an original and export copies for sharing. If a picture will be edited repeatedly, convert it to PNG first.
What JPG cannot do
It has no transparency, no animation, and it handles text, logos, and sharp lines badly, smearing halos around them. Use PNG or WebP for those. For the smallest files that still look good, WebP beats JPG by 25 to 35 percent at the same quality.
Frequently asked questions
Is there a difference between JPG and JPEG?
No. JPG is the three-letter extension from the days of DOS; the format is identical.
How do I make a JPG smaller?
Lower the quality to 75 to 85, or reduce the dimensions. Our image compressor does both and shows the before-and-after size.
Can I make a JPG transparent?
Not as a JPG. Convert it to PNG and remove the background in an editor.