It is a condensed form of Exchange Image File format which is basically a standard format set to report the various parameters of a photograph. The data that are captured mostly include the make of the camera, shutter speed, focal length, the aperture, ISO. When suitably available, location coordinates are also available in the EXIF data. Extra information as to whether the flash fired or not, or the shutter count of a camera can also be found by studying the data.
The EXIF Data for the above photo is shown here below as a screenshot from my phone.
This data is immensely useful if someone is trying to learn and take cues from other photographers as to what settings to be used in particular situations.
Do you check the exif data of other photogs?? Let me know!
This is the raw material for the slightly advanced HDR (High Dynamic Ratio) photos. Suppose, in a landscape, if we correctly expose the sky, the foreground is dark, and if we meter the foreground correctly, the sky is washed away. Instead, we take a series of photos exposing the various parts correctly, then we combine them in photo-editing software, and we have a composite photo, where everything is exposed correctly. Be careful though, aperture, focus and white balance must not change during the series. In some cameras, its an inbuilt function, others vary the shutter speed.