What EXIF is and what it says about you
EXIF is the technical record a camera writes inside every photo. Nobody sees it when looking at the picture, but anyone who receives the file can read it.
A standard from 1995
EXIF stands for Exchangeable Image File Format. It was published in 1995 by JEIDA, the Japanese electronics industry association, so that digital cameras could store the shooting data next to the photo: exposure, aperture, date. Today it is maintained by CIPA and JEITA, and practically every camera and phone writes it.
When phones with GPS arrived, the standard already had room for coordinates. And phones started filling it in by default.
Where it is stored
Inside the file itself, not next to it. In a JPEG it sits in a block at the start, before the image; in iPhone HEIC photos, in a box of its own inside the container; in PNG and WebP, in a separate chunk. That is why it travels with the photo wherever it goes: by email, on a USB stick, to the cloud.
Internally, EXIF uses the same structure as TIFF files: tables of numbered fields. Each field has a standard name —DateTimeOriginal, GPSLatitude, Model— and manufacturers add their own maker note, a private table where each brand stores whatever it likes.
The fields that tell the most
GPSLatitudeandGPSLongitude: where the photo was taken, to within a few metres. WithGPSAltitude, how high up; withGPSImgDirection, which way you were facing.DateTimeOriginalandOffsetTimeOriginal: the exact moment, to the second, and the time zone.MakeandModel: the device’s brand and model.BodySerialNumber: the camera’s serial number. Many DSLR and mirrorless cameras write it, and it links every photo taken with the same device, even when they are published in different places.ArtistandCopyright: whatever name was set in the camera or the editing software.Software: the program or system version that saved the file.- The thumbnail: a small copy of the photo stored inside the EXIF. Some programs crop the image without updating the thumbnail, so the cropped-out part is still there.
EXIF is not the only one
Next to the EXIF there are usually two other kinds of metadata. XMP, Adobe’s format, stores the editing history, ratings, keywords and sometimes the names of people recognised in the photo. IPTC is the news agencies’ format: author, caption, keywords, place.
And photos are not the only files with metadata. Phone videos store the location just like photos. A Word document or a PDF stores the author, the company, the dates and sometimes the comments. An MP3 carries tags that can include who encoded it.
Why it matters
A photo taken at home and sent with its location carries your address. A series of photos with dates and GPS draws your routines: when you leave, where you go, when you come back. And a serial number links photos you published separately, perhaps under different names.
This is not a theoretical risk: photo metadata has given away the location of people who did not want to share it, from fugitives to journalists and their sources.
How to see a photo’s EXIF
Drop the photo on the exif.es tool: you will see every field it carries, grouped by what it reveals, and the location on a map if it has one. Without uploading it anywhere.
Your system can show it too: on Windows, in the file’s properties, “Details” tab; on a Mac, in Preview, with “Tools → Show Inspector”; and on an iPhone, by swiping up on the photo in the Photos app. But none of them shows everything that is there.