The tagging system in Things is one of the most powerful available. At the same time, it is unobtrusive and uses only a minimum of screen real estate. In order for Things to be useful, it is not necessary to use tags at all. Indeed, no pixel of screen real estate is wasted for users who choose to work exclusively with the other features of Things.
The tagging system adapts to your needs. Here are some of the basic features:
A Magic Tag Bar
The Tag Bar is hidden unless there are actually any to-dos that have tags. When visible it will only show those tags that are used in the currently displayed to-do list. It is even a little smarter. If all to-dos in the currently displayed list share a common tag, then that tag is not shown at all, since filtering by it wouldn't make any difference. If a tag appears in the Tag Bar, then you can be sure that filtering by it will result in displaying a proper sublist of the current list.
The Tag Bar not only lets you filter by tags, but it also acts as a table of contents to the items in the current list.
Multiple Tags
Every item (To Do, Project, or Area) can have multiple tags. Here, the user assigned the context "Errand" and a priority of "High":
Managing Tags
By selecting Window > Tags in the menu or clicking the corresponding Toolbar button, you bring up the Tags window. Using the Tags window, tags can be reordered, added, or deleted.
Tags can be assigned with a keyboard shortcut. Whenever you create a new tag, a unique shortcut will be generated for you. You can edit this shortcut in the Tags Window. To add or remove a tag using shortcuts, simply select the to-dos you'd like to change and press the corresponding key.