Atlassian Description: "Defines the appearance of the dashboard and a user's profile."
Found In: Administration
This is a special layout section that only exists at the top Confluence level, not is spaces.
The Dashboard is a unique "page" entity that cant be edited as pages, but is defined as partly HTML, partly scripting.
This is where You define the look of the Dashboard, which is default landing page for users.
Notice, the editing is directly and there is currently no versioning, so be carefull 
As this is not via the RTE, scipting (like in Macro(s) ) are used, and rendering a Macro is like:
$helper.renderConfluenceMacro("{jiraissues|max=100|page=10}")
Hence Macro and Wiki Markup in a mix..
Scopes for Confluence CSS Styling