When a text editor is chosen, we are given the option to configure CKEditor. As we can see, there are a multitude of Available buttons to select from that can be added to the Active toolbar. Buttons can be added by simply dragging them from one location to another.

Hovering over each button will display a brief explanation of what action each button performs. It is up to site builders to determine which buttons make sense for users to have access to when creating content.