metadata and tagging
darktable allows you to store additional information about your images to allow them to be more easily searched and grouped. This information is stored in darktable’s database and XMP sidecar files and can also be included within exported images.
Metadata (e.g. title, description) is free-format text that usually differs for each image.
See the metadata editor module for details of how to add metadata to images.
Tags are usually shared between multiple images and are used to categorise and group them.
See the tagging module for details of how to add tags to images.