Cheatsheet: 

Dashboard > Curation > Items > Edit Item > Tags

You may have heard the term "folksonomy" before. In short, a folksonomy is a user-generated vocabulary for describing and organizing content. It's metadata lite. For example, you might create a tag called, "Uncle Bill," for pictures of your uncle Bill or items belonging to him. You might create a tag called "wrenches" or "france" to help you organize and sort your items in a way that is logical to you. Tags are great for describing things in ways that don't conform to rigid metadata standards. 

You can add tags to an item on the Item Details page while in curation mode by going to Items > Edit

To add tags, separate your terms by commas. New boxes will appear with your terms which you can delete by clicking the "x"