Other CMS system calls this category. Since DotShoppingCart has already the product category we use content group rather than category to avoid confusion. You use content group to group articles together. Content groups can be orgnized as tree style hierarchy. You put sub content groups under one content group. When user clicks to see the content group all the articles under the content group including sub content groups will be dispalyed. 

To add a content group, in Content -> Content click "Add" button. Enter a unique content group name.  In Parent Group choose a parent group that you want to put the current group under. Choose "Top Level" if you don't want parent for the group. The default view is how the content group will be displayed. Article View is what you usually see from someone's blog, e.g. DotShoppingCart Blog. Hierarchy view is what you usually see from online help or FAQ. Forum view makes it a forum. Choose the view that you wish to display the content. Enter sort order for the content group. The sort order affects views other than Article View. The artcile view uses the created time of the articles to decide the order article displays. In other views the value of sort order decides which conent group displays first. The smaller value of sort order the higher priority it displays. Set the correct permission for the content groups. Click"Add" button to save the changes.