Tags are labels you choose: anything you will want to find items by.
- One item — More → Edit tags…, or the tags in its form. Enter or a comma adds a tag.
- Many items — select them in Holdings, then Add tags… or Remove tag…. See Selecting many items.
- Rename or merge — More actions → Tags & locations…. Renaming onto an existing tag merges the two.
Filter by a tag with Any tag in Holdings; tags are searchable too.