// mime type · image type
image/jpeg
JPEG image · .jpg
What image/jpeg is
image/jpeg is a lossy compressed image (.jpg), best for photographs. It trades some quality for much smaller files, but has no transparency.
How it's used
You'll see this as a Content-Type value on requests and responses — for example Content-Type: image/jpeg. It's the type associated with the .jpg file extension. Image types tell the browser how to decode and render a picture.