An XMP file is a small text “sidecar” that sits next to a photo — same name, .xmp extension — and stores information about that photo: the metadata (caption, copyright, keywords, camera settings) and, for RAW files, the editing instructions from apps like Lightroom Classic, Camera Raw, or Capture One.
The image itself is never altered; the XMP carries the notes. They’re tiny, harmless, and safe to leave alone — and if you delete one, you lose those notes, not the photo.
That’s the one-paragraph answer. The rest of this post covers what’s actually inside an XMP file, why Lightroom and other apps create them, how to open one, and the practical questions — can you delete them, should you send them with a photo, and how they differ from the metadata embedded inside a JPEG.
XMP files at a glance
| Question | Answer |
|---|---|
| What is it? | A plain-text metadata file in XML format, written to the Adobe-originated (now ISO) XMP standard |
| What’s inside? | Descriptive metadata (title, caption, keywords, copyright, ratings), camera/EXIF data, and per-app edit instructions (Lightroom/Camera Raw develop settings, Capture One adjustments, etc.) |
| Which files get a sidecar? | Mostly RAW files (NEF, CR3, ARW, RAF, ORF…), which apps won’t write into. JPEG, TIFF, DNG, PSD usually carry XMP embedded inside the file instead |
| Which apps create them? | Lightroom Classic, Adobe Camera Raw/Bridge/Photoshop, Capture One, darktable, Photo Mechanic, DxO PhotoLab, and most serious RAW editors |
| Can I delete them? | Yes without harming the photo — but you lose the edits/metadata they hold unless the app also keeps them in its catalog |
| Do I send them with a photo? | Not for JPEGs. Only if you’re handing a RAW file to someone who should see your edits |
| How do I open one? | Any text editor; photo apps read them automatically |
| Size | A few KB, even for heavily edited files |
XMP files aren’t actually image files, but they are closely related. And there’s a good chance you’ll run into them as you’re editing your photos.
XMP files are what are known as sidecar files. They’re designed to go alongside the image file, and they provide extended metadata information.
XMP files are text files that provide information about an image file that’s associated with it. So the logical place that you’ll run into them is alongside an image file. For convenience, they usually have the same filename, differing only with the file extension.
XMP stands for Extensible Metadata Platform. It’s a system originally devised by Adobe and has since become an ISO standard.
And I’m referring in this post to XMP files — the ones you see with an .xmp file extension — which is an implementation derived from that system.
Many image file formats, of course, have provisions for embedding metadata information inside them. So JPGs, for instance, might have quite a lot of text information including, such as the camera model, the date, the GPS location, a caption, copyright status and usage rights, and so on. Much of that can be contained in EXIF or IPTC metadata fields.
XMP builds on that idea, and it is also used as the standard system for embedding information inside image files without breaking the image files’ compatibility. So XMP information can be embedded inside some image file formats (but not all).
But there are two reasons separate XMP sidecar files serve a purpose.
- One is that they can be edited without altering the original file. That’s especially important in the case of RAW files, which are really designed to be treated like digital negatives and never directly edited (that’s where a non-destructive editing workflow comes in).
- The second area is that an XMP sidecar file provides far more space and flexibility for far more information. That includes adding whole sections that software designers or camera manufacturers might want to add for customized (and even proprietary) information. For instance, it might include protected information on how a Lightroom filter should process the image. Or a camera manufacturer might include data about the image that only the camera manufacturer’s products can access.
XMP vs XML
XMP and XML are related, but they’re not the same thing.
XMP stands for Extensible Metadata Platform.
XML stands for Extensible Markup Language. It’s a way (or language) for structuring and presenting textual information. It’s known as a markup. It’s designed to be logically structured and readable by humans. It can apply to many different types of information.
XMP files are special kinds of files that are structured using XML.
The XMP system (or platform, technically) is designed in such a way that different apps can add their own data to the XMP file without disturbing the other data that’s already there. So if you edit an image in, say, Lightroom, then edit it in Photoshop, and then export it from Photo Mechanic, each of those apps will store its information in its own distinct packet within the XMP file, and you can go back and forth between apps without losing information.
How to open an XMP file
You rarely need to open one by hand — Lightroom, Bridge, Capture One and the rest read it automatically when they open the photo beside it. But if you’re curious (or troubleshooting), any text editor will do: TextEdit on a Mac, Notepad on Windows, or a code editor. What you’ll see is XML — structured, human-readable, and full of namespaced fields. Here’s a trimmed example from one of my own sidecars, with the Lightroom develop settings visible in the crs (Camera Raw Settings) section:
crd/crs fields), then camera and exposure data. Same information Lightroom shows you, just in raw form. Photo by David Coleman / Have Camera Will Travel<x:xmpmeta xmlns:x="adobe:ns:meta/">
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
<rdf:Description
xmlns:xmp="http://ns.adobe.com/xap/1.0/"
xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:crs="http://ns.adobe.com/camera-raw-settings/1.0/"
xmp:CreatorTool="Adobe Photoshop Lightroom Classic"
xmp:Rating="3"
crs:Version="17.0"
crs:HasSettings="True"
crs:WhiteBalance="As Shot"
crs:Exposure2012="+1.21"
crs:Contrast2012="0"
crs:Highlights2012="-11"
crs:Shadows2012="-26">
<dc:rights><rdf:Alt><rdf:li xml:lang="x-default">Copyright David Coleman</rdf:li></rdf:Alt></dc:rights>
</rdf:Description>
</rdf:RDF>
</x:xmpmeta>Every app writes into its own section — Lightroom in crs, captions and copyright in dc and photoshop, and so on — which is how several programs can share one sidecar without trampling each other’s data.
Why did Lightroom create XMP files next to my photos?
Because you (or a default) told it to. Lightroom Classic keeps your edits and metadata in its catalog database; with Catalog Settings → Metadata → Automatically write changes into XMP switched on, it also writes them out to a sidecar beside each RAW file. That’s a good thing: the edits survive outside the catalog, other apps can see them, and a reimport keeps your work. You can also do it on demand with Metadata → Save Metadata to Files (Cmd/Ctrl-S in the Library module). If you never asked for sidecars and they appeared after using Camera Raw, Bridge, or Capture One, same idea — those apps default to writing them.
XMP sidecar vs. embedded metadata
The same XMP data can live in two places. For JPEG, TIFF, DNG, and PSD files, apps write it inside the file, so there’s no sidecar — the metadata travels with the image wherever it goes. For camera RAW files, apps treat the original as untouchable and write the XMP to a separate sidecar instead. That’s why a folder of NEFs sprouts .xmp files and a folder of JPEGs doesn’t. If you need metadata to travel with a RAW file, either send the sidecar along or convert to DNG, which embeds it. (Which formats embed what is covered in my guide to image file formats.)
Practicalities of working with XMP files
There are a few things worth knowing about working with XMP files.
Can I delete XMP files?
It depends. If you delete an XMP file, it doesn’t affect the original image file next to it. But you still might lose important information.
That could include any text metadata you’ve added (captions, etc), or it might include any editing instructions or filters that were applied in an app like Lightroom or Capture One.
If you delete the XMP files and then reopen the images in an image editing app, any previous edits might be lost. But it’s also possible they won’t be. That’s due to the way in which image editing apps like Lightroom save their information. The quickest way to do that is for them to use their own internal database. Depending on the app’s setting, they might then save much of that information into the XMP files.1
In practice, XMP files are so small in file size — at least compared to the image file itself — that there’s really no need to delete them to save space.
Can I edit XMP files?
As a technical matter, it’s possible to edit XMP files directly with a text editor. They’re specifically designed that way, in accordance with XML standards. XML is designed to be human-readable (and therefore human-editable). If you need to batch process a caption or copyright field, for example, you can.
But most of the time, you never need to work directly with the XMP files. And it’s rarely a good idea to edit the data directly because of the risk of introducing a syntax error or making a coding error. Miss a comma or closing bracket here or there, and you might end up with a non-validating corrupted file. There are usually better and safer ways to tackle it, such as editing the metadata through an app like Photo Mechanic or Lightroom, which ensures that the file is structured as it should be and all the technical syntax is in order.
Do I need to send the XMP file with the photo?
No, not normally. In general, XMP sidecar files can be treated as archival files that stay with the original master images. And most image file types that are more commonly used for publishing and sharing photos — JPEG, WebP, or AVIF, for example — have their own provisions for embedded metadata inside the file.
A rare exception might be if you’re sharing a RAW file with a fellow photographer or graphic artist. In that case, bundling the XMP file with the RAW file would allow them to preserve any edits you’ve made.
What kind of information is included in an XMP file?
The information in any given XMP file will depend on what the image has been edited in. The most basic kind of information that’s most commonly present in XMP files associated with a photo captured by a camera is probably EXIF information, which is information about the capture (capture device type, model information, exposure information, etc).
If you’ve edited the image in an app, that app might have saved its own packets of information. Many of the XMP files with my images, for example, reflect a workflow that incorporates Photo Mechanic, Lightroom, and Photoshop. If you’re using PLUS licensing data, that would be included.
