Exchangeable image file format (officially Exif) is a standard that specifies the formats for images, sound, and ancillary tags used by digital cameras, including smartphones. This data is often appended to JPG files, and can tell you when the photo was actually taken, plus other settings. You can actually modify these properties, and there are a few tools great at doing that.
Editing Exif Data
- The theExifer... just a web base exif editor - Online tool which let's you upload a JPG, modify the Exif in a nice editor, and then download the modified version.
- Adobe PhotoShop .... you can click "File > File Info" and modify some of the EXIF settings, but not all (not all date stuff), so that sucks.
- Exif - Wikipedia
- EXIF Data – All You Need To Know About Using & Manipulating The Data .... some little tips for different operating systems.