EXIF stands for Exchangeable Image File Format and can be found inside digital images.
This type of specification is supported by JPEG and TIFF files, and is not available in PNG or GIF files.
EXIF features details related to the date when the photo was taken, the camera manufacturer and model, aperture, resolution, orientation, exposure and so on.
EXIF editors enable their users to modify these details according to their needs, or remove them altogether.
Also, it is usually possible to insert EXIF data within photos in order to easily remember the location or the date the picture was taken.