What is a .jpg file?

About the format

A .jpg (or .jpeg — identical format, the three-letter variant is a DOS-era relic) is a photograph-oriented image using lossy compression: it achieves small files by discarding visual detail the eye misses, which is ideal for photos and wrong for screenshots, text or diagrams, where the discarded detail shows up as smudgy artefacts around sharp edges (use PNG for those). Two practical JPEG facts earn their space here. First, quality is a one-way street: every re-save at JPEG compression loses a little more, so edit from originals and export once. Second, metadata: JPEGs carry EXIF data — camera model, timestamps, and often the GPS coordinates of where the photo was taken. Photos shared directly (email, cloud links) usually keep that data; most social platforms strip it on upload. Windows shows EXIF under Properties → Details, with a 'Remove Properties and Personal Information' link when you want a clean copy before sharing.

How to open a .jpg file

Is a .jpg file dangerous?

Effectively no for viewing (image-decoder exploits exist but are rare and patched fast). The real consideration is EXIF location data in photos you share.

Related file types