Once you host your web site (domain) through any web hosting provider, you will need some interface to manage your web site (domain). Without any interface, it is hard to manage your web site. The interface through which you can manage your web site (domain) is called web hosting control panel.
There are many web hosting control panels available. Some of them are HELM (only for Windows server), cPanel/WHM (For Linux server), Plesk (Windows and Linux servers), DirectAdmin (Linux) Ensim etc. Using the control panel, you can manage your web site (domain) easily from any where. It allows you to create the email accounts of your web site (domain), to set the email forwarder for your email accounts, to add the domain alias (domain parking), to modify the web pages of your web site through file manager, to create the databases for your web site (domain) etc. Many control panels allow you to modify your DNS zone of your website. Hence, you do not need to contact your hosting provider in order modify some records in the DNS zone of your domain (i.e. A record, MX record, add CNAME). In same way many control panels allow you to upload your web pages directly through control panel and you can zip or unzip the folder through control panel itself.
If you have your own dedicated server then you can manage the web sites without any web hosting control panel. However, it would be easy to setup your server using the hosting control panel as it provides the user friendly interface.
Below are the some web sites for web hosting control panel product:
You should upgrade your control panel regularly to fix the bugs in the current version of the control panel and improve the security of your server.