In Salesforce Knowledge, a category group organizes data categories into a logical hierarchy. For example, to classify articles by sales regions and business units, create two category groups, Sales Regions and Business Units. The Sales Regions category group could consist of a geographical hierarchy, such as All Sales Regions as the top level, North America, Europe, and Asia at the second level, and so on up to five levels. When creating articles, authors assign the relevant categories to the article. End users searching for articles can search and filter by category.