EXIF
Exchangeable Image File Format (EXIF) is the metadata that cameras and phones write into a photo file automatically when it is taken.
Common fields
| Field | Meaning |
|---|---|
| Make / Camera Model Name | Device maker and model |
| Date/Time Original | When it was taken (local time) |
| Offset Time Original | The time zone offset when it was taken, e.g. +08:00 |
| GPS Position | Where it was taken (if location was on) |
| Software | Software that processed the image |
How to read it
The command-line tool exiftool is the most common way: exiftool file.jpg
Privacy risks
Many people think turning off location is enough, but the device model, time zone and time stay in the file. Big social networks usually strip EXIF on upload; forums, email attachments and cloud drives often keep the original file.
Further reading: anoni.net concepts (external, in Chinese) · How phone cameras name their files