Tags, or identifiers, can be added by hand or automatically imported when you import citations.
All tags currently in your library are listed on the bottom left of your desktop Zotero.
To see tags affiliated with a particular item, click on its name and select "Tags" at the top of the pane to the right.
To see articles affiliated with a particular tag, click on the tag and Zotero will show you the articles in your Library that include that tag.
Searching Your Zotero Library
You can search materials by Title, Creator, Year, All Fields & Tags, or Everything by typing in your search terms in the bar at the top of your Zotero desktop. Use the dropdown menu to specify where you would like to search. This method will also search the full text of website snapshots.
In addition, Zotero has many options you can use to sort the materials in your LIbrary. Sorting will allow you to search materials using the following categories: Creator, Item Type, Date, Year, Publisher, Publication, Date Added, Date Modified, Extra, Attachments, Notes, etc.