A Control Panel is a web-based user interface where you can handle various aspects of your presence online. For example, you could set up or change site files, set up and check emails, manage databases, check visitor stats and so forth. These things are done using buttons and menus within a browser and the CP could also be called ‘back office’, i.e. the administrative area associated with your website hosting account. Most Control Panels out there will allow you to control all hosting-related matters, but you'll usually need a different system to deal with payments or to get a new domain if the company offers domain registrations. Depending on the platform they use, you may be able to use the billing account to open a support ticket to ask a question or to diagnose a problem as well, or you might have to use a 3rd system.