cPanel & WHM is an online Linux-based web hosting control panel that provides a graphical interface (GUI) and automation tools designed to simplify the process of hosting a web site to the website owner or the "end user". cPanel & WHM utilizes a three-tier structure that provides capabilities for administrators, resellers, and end-user website owners to control the various aspects of website and server administration through a standard web browser. While cPanel is limited to managing a single website, the server administration panel is called WHM, short for WebHost Manager.
The WHM is designed to function either as a dedicated server or virtual private server. The latest cPanel & WHM version supports installation on CentOS, Red Hat Enterprise Linux (RHEL), and CloudLinux OS. cPanel 11.30 is the last major version to support FreeBSD.
Application-based support includes Apache, PHP, MySQL, PostgreSQL, Perl, and BIND (DNS). Email-based support includes POP3, IMAP, and SMTP services.
Once installed, WHM cannot be easily removed. WHM FAQ states that the best way to uninstall cPanel & WHM is by reformatting the server. However, uninstall guides are available online for expert server administrators who do not wish to reformat their server. Similarly, it should only be installed on a freshly installed operating system with minimal prior configuration
Read More (Wikipedia)