Every image stores various amounts of metadata. For example, there is EXIF metadata, which describes the camera and lens that captured the image, as well as f-stop, shutter speed and a plethora of additional information about how the image was captured. In addition, images can also contain custom metadata information (such as that defined by IPTC) including the copyright, contact information, rights usage and so on.
Typically photographers want this metadata to travel with their files, but every once in a while I am asked how to remove the extraneous metadata when exporting a file to be delivered to a client. To remove all metadata in an image (including camera settings, ratings, develop setting, etc.) except the Copyright Notice and Copyright Status upon export, check the box next to “Minimize Embedded Metadata” in the Export dialog.
Note: The develop settings will still be applied to the image on export so the image will look as you intended, but the settings will not be embedded in the file.
If you need to selectively strip metadata from exported images, check out Jeffrey Friedl’s Metadata Wrangler.
And, if you want to see even more metadata than lightroom displays, check out Jeffrey Friedl’s Metadata Viewer.