Found In: Confluence Administration -> Look And Feel -> Layouts -> Global Layout
This is a special layout section that only exists at the top Confluence level, not in spaces, Atlassian description is: "Defines the appearance of the dashboard and a user's profile."
The Dashboard is a unique "page" entity that cant be edited as pages can, 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..