Control Panels
What is a control panel?
A control panel is a GUI (graphical user interface) that let's you manage your websites and server in a quick and easy way.
Control panel software comes pre-installed with most hosting plans, however VPS and dedicated hosting may sometimes offer a hosting plan without control panel. Although you save a couple of bucks on the control panel software, this is only intended for experienced administrators who know how to do everything by just using the command line tool.
Let's have a look at two popular control panels.
cPanel and WHM
It's safe to say that cPanel is the most used control panel. Nearly every serious web host offers it.

Although the user interface may appear quite simplistic, cPanel shines with its ease of use and powerful features.
Pretty much everything is tied into the control panel, from databases to email settings and statistics software. You can setup a fully functional website with just a few mouse clicks.
The downside is that cPanel costs a bit more than its competitors.
WHM (WebHost Manager) is the top-level control panel to access the server and all cPanel accounts. WHM is an administrator tool, thus, you'll only need it if you have a VPS or dedicated server.
Plesk
Plesk is a good and somewhat cheaper alternative to cPanel.
It's known for being very stable. Compared to cPanel it offers less features, though this is improving with every new release.
It also looks prettier which can be a plus if you're reselling your web space to non-technical customers.
Unlike cPanel, Plesk also has a working Windows version (though cPanel is in the process of developing one, too, as of writing this).