All hierarchical structures have to start somewhere and in our case it's the ROOT skin. This contains a basic design (based on the default design of Confluence 5) and is the foundation for all the other skins.
In most cases this won't be the design you want for your wiki but it's a useful starting point for your own designs. To prevent space administrators from choosing the root skin you can restrict who can select the skin on the Permissions Tab.
You can attach a skin to another skin (the "parent" skin) in order to inherit settings from that parent skin as shown below:
The most common scenario is that you'll want to make a skin that has the general design required by your organisation, but then have other skins that look similar but change things such as navigation, which panels are shown, colours, etc.
If you change a setting in a parent skin then, as long as the child skins don't override that setting, all the child skins will immediately be updated to reflect the change:
If desired, you can set all the settings back to default (ie. make everything in your skin inherit from its parent skin) using the "Revert" button on the.