You can assign one or more tags to selected photos. A tag can be one or more words that you want to associate with those photos.

To add new tags to photos, select the photos you would like to tag, then do any of the following:

When you use CtrlT or TagsAdd Tags... you can type in the names of one or more tags, separated by commas. You can also add tag hierarchies on the fly using / as if they were paths in the file system. Once you have created a tag, you can rename it by selecting that tag in the sidebar and choosing TagsRename Tag "[name]"..., by right-clicking on it and choose Rename... or double-click on the tag in the sidebar.

To change which tags are associated with a particular photo, select that photo, choose TagsModify Tags... or right-click on a photo and select Modify Tags... and edit the comma separated list. To remove a tag from one or more photos, first select that tag in the sidebar, then select the photos you would like to remove, and choose TagsRemove Tag "[name]" from Photos or right-click on the photos and select Remove Tag "[name]" from Photos.

To delete a tag entirely, select that tag in the sidebar and choose TagsDelete Tag "[name]" or by right-click and select Delete Tag "[name]".

When you create a tag, it will appear in the sidebar under the Tags item, which is hidden if there are no tags. Photos can have multiple tags attached to them, and when you click on the name of a given tag in the sidebar, you will see all the photos associated with that tag.