Image Metadata Explained
Three standards, written by three different things, with three different fates when you edit a file.
"Image metadata" is not one thing. A photograph can carry three separate blocks, added at different points in its life by different software, and most confusion about metadata comes from treating them as interchangeable.
EXIF — written by the camera
Exchangeable Image File Format. The device writes it at the moment of capture: make and model, lens, shutter speed, aperture, ISO, orientation, the date and time, and GPS coordinates if location was enabled.
This is the block that raises privacy questions, because it is the one that records where you were standing. It is also the block almost every tool can read — including the EXIF viewer here.
IPTC — written by people
A standard from the International Press Telecommunications Council, designed for news photography, and still the backbone of how images are described in publishing: caption, headline, photographer, credit line, source, keywords, and usage terms.
Where EXIF says 1/250s at f/2.8, IPTC says protest on Nguyen Hue street, photograph by X, editorial use only. Cameras do not write it; photographers, agencies and asset management systems do.
XMP — written by software
Adobe's Extensible Metadata Platform, which stores metadata as XML inside the file. It can express IPTC fields, plus edit history, ratings, colour labels and application-specific settings.
Most modern photo software writes XMP, often duplicating the same caption into IPTC and XMP so older tools still see it. That redundancy is why a single field can appear twice with different values if something updated one and not the other.
Side by side
| Written by | EXIF: the camera · IPTC: people · XMP: software |
|---|---|
| Describes | EXIF: how it was taken · IPTC: what it shows and who owns it · XMP: both, plus editing state |
| Format | EXIF and IPTC: binary records · XMP: XML |
| Privacy risk | EXIF: high — GPS and device IDs · IPTC and XMP: whatever a person typed |
| Read by | EXIF: nearly everything · IPTC and XMP: photo and publishing software |
What happens when you edit an image
This is where most metadata gets lost, usually without anyone noticing:
- Resizing, compressing, converting format — the image is redrawn, and a redraw keeps pixels only. All three blocks go.
- Uploading to a social platform — the platform re-encodes, so the same thing happens. This is why a photo saved from Instagram reads as empty.
- Editing the metadata block — the picture is untouched, but the editor writes back the fields it knows about. A tool that handles EXIF will not preserve XMP it never read.
- Deliberate removal — see removing EXIF data.
The practical rule: do metadata work last. Get the image to its final size and format, then write the fields that matter.
Which one should you care about?
- Worried about privacy? EXIF. That is where GPS and device identifiers live — check then strip.
- Publishing your own photographs? IPTC and XMP carry credit and rights. A photo manager writes them on import; the metadata editor here writes the EXIF artist and copyright fields, which is enough for most casual use.
- Organising a library? XMP, because that is where ratings and keywords live.
- Fixing a wrong date? EXIF — the date taken field.
Metadata is not evidence
All three blocks are written by software and editable by software. Timestamps come from a device clock that may never have been set; locations can be added to a photo taken anywhere; captions are typed by whoever had the file last.
Metadata is a strong hint and a useful cross-check. Its absence proves nothing at all — the most common reason for a photo to have none is that it passed through a website.
Frequently asked questions
Why does the same caption appear twice?
Because software often writes it into both IPTC and XMP for compatibility. If one is updated and the other is not, they drift apart and different applications show different text.
Do PNG and WebP carry metadata?
They have their own containers — text chunks in PNG, dedicated chunks in WebP — and both can hold XMP. Support is far patchier than for EXIF in JPEG, so metadata in those formats travels less reliably.
What reads all three?
ExifTool on the desktop is the reference implementation and handles essentially every standard and format. Browser tools, including the ones here, focus on EXIF because it is the block that matters most to most people.
Related guides
- What is EXIF data — every field, explained
- How to edit image metadata — reading, editing and removing
- Removing EXIF data — and why it matters
Summary
EXIF comes from the camera and describes capture, IPTC comes from people and describes content and rights, XMP comes from software and carries both plus editing state. EXIF is the one with the privacy implications and the one nearly every tool can read. Anything that redraws an image drops all three, so write metadata last.