Format Odyssey

FILE FORMAT GUIDE

JPG File (.JPG): What It Is & How to Open It

A JPEG file stores a JPEG-coded image, commonly in JFIF or Exif-oriented interchange structures. The .jpg and .jpeg extensions do not by themselves distinguish those wrappers.

Quick facts

Extension
.jpg, .jpeg
Format
JPEG Image
Category
image
MIME type
image/jpeg
Standard / developer
ISO/IEC and ITU-T
Open with
Photos, Preview, or a web browser

What is JPG?

Every JPEG bitstream begins with the Start of Image marker FF D8. Bytes after that marker distinguish structures such as JFIF APP0 or Exif APP1; a longer JFIF signature must not be required for every JPEG.

How to open JPG

Photos, Preview, or a web browserWindows / macOS / Web

Double-click the image to use the system photo viewer, or drag it into a current browser window. Use an image editor when you need to change pixels or export settings.

JPEG image format — MDN Web Docs

Common uses and compatibility

  • Store and exchange compressed photographic images

Things to check

  • Repeated lossy editing can introduce further degradation; JFIF-specific bytes are not universal to every JPEG wrapper.

Advanced inspection

These developer and command-line workflows inspect structure or metadata. They are not the default way most people open the file.

ImageMagick identifyCommand-line tool

First run magick identify -list format and confirm JPG read support in this installation. Then run magick identify -verbose -- input.jpg to inspect the format and image characteristics without overwriting the source.

Technical details

Signature
FF D8 (JPEG Start of Image)
Encoding
Not applicable
Container
JPEG marker stream; commonly JFIF or Exif-oriented
Compression
Usually lossy JPEG coding; the family also defines lossless processes

JPEG File Interchange Format family

Related formats

  • Portable Network Graphics

    PNG is a lossless raster alternative with a chunk-based structure and different transparency workflow.

  • WebP Image

    WebP is a RIFF-based alternative that can store lossy or lossless image data.

  • AV1 Image File Format

    AVIF uses ISO Base Media File Format structures and AV1 coding, while JPEG uses the JPEG codestream family.

Sources & review

Sources reviewed 2026-09-19.