What your photos reveal
A photo file is an image plus a dossier. EXIF holds the GPS coordinates, the camera and lens serial numbers, the firmware version and the exact second of capture. IPTC and XMP hold your name, your copyright line and edit identifiers that link one file to another. On a Mac, open the photo in Preview and press Cmd-I to see most of it.
What is actually in there
Three separate metadata systems usually ride along in the same file.
EXIF is the camera's own record. Make, model, lens, focal length, aperture, ISO, orientation, firmware version, and two fields that surprise people: the body serial number and the lens serial number. It also carries the capture timestamp down to the second, often with a time zone offset, and if location services were on, GPSLatitude and GPSLongitude plus altitude and heading.
IPTC is the publishing layer: creator, credit, copyright notice, city, state, country, keywords and captions. Photo apps and stock workflows fill these in, sometimes automatically from your account name.
XMP is Adobe's layer, and the one people forget. It stores DocumentID, InstanceID and OriginalDocumentID, which are identifiers that survive editing and let two exports be recognized as versions of the same original. It also duplicates location fields such as photoshop:City and photoshop:Country.
Why the serial number matters more than the GPS
Everyone worries about coordinates, and they should: a holiday photo posted publicly is one thing, a photo of a pet in a back garden is a home address.
The serial number is the quieter problem. It is stable across every photo that camera ever takes. Post one photo with your real name attached and another anonymously from the same body, and the two are linkable by a field neither of them displays. The same holds for the lens serial and, on phones, for the private Apple maker-note dictionaries that ride inside HEIC files.
Location can be worse than the coordinates suggest, too. GPSAreaInformation occasionally carries the name of the WiFi network used for the location fix, which is a different kind of identifier entirely.
But social networks strip this, right?
Mostly, on the big ones, on the public upload path. That is a thin protection to rely on. EXIF stays intact when you:
- Send the file as an email or chat attachment rather than through a photo picker.
- AirDrop it.
- Upload it to Slack, Discord or a shared drive.
- Put it on your own site or in a listing, where nothing strips anything.
- Hand it to a client, a printer or a marketplace.
Platform stripping also removes nothing from the copy sitting in your Downloads folder, which is the one you will forward next month.
How to check a photo on your Mac
| Method | What you get |
|---|---|
| Preview, then Cmd-I | The Inspector. The General, EXIF, IPTC and GPS tabs, with a map pin if coordinates are present. |
| Finder, then Cmd-I | Get Info. Basic dimensions plus the "Where from" line if it was downloaded. |
mdls photo.jpg | Everything Spotlight indexed, including kMDItemLatitude and kMDItemLongitude. |
Preview is the fastest check and the one to teach people. If the GPS tab exists at all, the file knows where you were.
Getting it out
Preview will show you the metadata but will not remove it. Photos can export without location, and that helps, but it leaves the rest of the EXIF and it only covers files in the library.
Two things worth knowing before you strip anything:
- Stripping metadata from a JPEG or HEIC means the image gets re-encoded. The metadata blocks are woven into the image structure, so the file is rewritten rather than trimmed. Keep your original, and do not expect the output to match the input byte for byte.
- Check the result. Plenty of tools mark metadata as removed while leaving a copy in a second block, typically XMP that survives when EXIF is cleared. Re-open the cleaned file and look again. A cleaning step you never verify is a habit, not a protection.
File cleaning is coming next to tdy.
tdy is a Mac menu-bar app that already tidies every link you copy. Stripping EXIF, GPS and the rest out of files before you share them is on the way. One email when it ships, nothing else.
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