A photo’s EXIF data holds a lot of information about your camera, and most likely where the picture was taken (GPS coordinates). So if you are sharing the images online, there’s a lot of details others can take from them. EXIF stands for Exchangeable Image File Format. Every time you take a picture with your digital camera or phone, a file (typically a JPEG) is written to your device’s storage. In addition to all the bits dedicated to the actual picture, it records a considerable amount of supplemental metadata also. Sometimes it will include time, date, camera settings, and possible copyright information. You can also add further metadata to EXIF through photo processing software.
A camera phone or digital camera with GPS capabilities can record EXIF geolocation metadata. This can be useful if you are wanting to geotag but it may allow users to see any images taken in specific locations, view where the pictures were taken on a map, and to find and follow social events.
EXIF and geotagged data also provides a lot of information about the photographer, who may or may not want to share all of the information.