The Control Panel
Also known as the “CP”, “admin area”, or “back end,” the Control Panel is where most of your interaction with ExpressionEngine will take place. Here you’ll publish and edit your content, control the look and feel of your site, manage your members, and much more.
If you are a site builder you will primarily interact with the cluster of links on right side of the navigation, if you are a content creator then you’ll typically use the links on the left.