EXIF
Also known as: Exchangeable Image File Format, EXIF metadata
EXIF (Exchangeable Image File Format) is the metadata standard cameras and phones embed inside JPEG photos — including GPS coordinates, camera model, capture timestamp, and shutter settings — which is why a holiday photo can quietly leak the exact street address it was taken at.
Overview
Every JPEG you take with a phone or modern camera carries an EXIF block — a binary chunk of tagged metadata wedged into the file's APP1 segment. The tags include capture timestamp, camera make and model, lens, ISO, shutter speed, aperture, and frequently a GPS latitude/longitude pair pinning the photo to the second the shutter clicked.
This metadata is incredibly useful for photographers and forensic analysts — and incredibly leaky for everyone else. A photo of your living room you posted publicly to ask for furniture suggestions can give a stalker your home address. Many social networks strip EXIF on upload; many file shares do not. If the privacy floor matters, strip the metadata locally before you upload anywhere.
EXIF is JPEG-specific. PNG has its own metadata layout (tEXt and iTXt chunks); WebP has its own EXIF chunk. Stripping in-browser walks the file's segment markers and removes the metadata blocks without re-encoding the image.