Use this menu selection to assign a keyword (or multiple keywords) to the selected thumbnail(s). You may either select an entry from the drop-down list or type new keyword(s) in the edit field.
Note: You can assign multiple keywords to the file (or files) by separating each with a semi-colon (;).
You may search for images using keywords you have assigned by using the Edit | Find by Query - Keywords selection from the main menu. You can have ThumbsPlus automatically assign some keywords using Options | Preferences - Keywords.