Adding a tag in boards simply categorizes the board in the learning view.

The tags can be clicked on to filter the boards

Adding a tag

In authoring, to add a tag on a board simply click on 

Choose an existing tag OR click Add New

Why do I see a star/asterisk(*) next to my tags?

This means that there is a difference between the published (live) board versus your current revision of the board. You may have added a new tag or deleted a tag. Once you've publish the asterisk will disappear.

Remember

Make sure to press the PUBLISH / PUBLISH CHANGES to make the changes lives.