ProWorkflow offers three main tools for Categorization. These are as follows:
Work Stages - these can be used to designate the stage that a Project, Item, Invoice, or Quote is at. Work Stages are also how you change a Project, Item, Invoice, or Quote to a "Completed" or "Deleted" state. To learn more about using Work Stages please see this help article.
Categories - these are color coded labels that you can apply to Projects or Items. They are more static than Work Stages, and cannot be used to actually affect the status of a Project or Item i.e. delete or complete them.
Tags - Similar to Categories, Tags are color coded labels that can be applied to Projects, Items, or Contacts. They also cannot be used to affect the status of a Project/Item/Contact.
The options for all three of these categorization tools can be managed in your Settings.