The <regions:content />
tag defines the area in the design where the page's editable content is rendered.
Each design needs to have exactly 1 content region visible at any one time (as Pages only have 1 primary content).
Multiple can be present if they are surrounded by <logic:if>
tags to create different scenarios inside the design.
If more editable regions are required, the <regions:contentadditional>
tag can be used.