From Wikipedia ...

cPanel is a linux based web hosting control panel that provides a graphical interface and automation tools designed to simplify the process of hosting a web site. cPanel utilized a 3 tier structure that provides functionality for administrators, resellers, and end-user website owners to control the various aspects website and server administration through a standard web browser.
 In addition to the GUI interface cPanel also has command line and API based access that allows third party software vendors, web hosting organizations, and developers to automate standard system administration processes.

cPanel is designed to function either as a dedicated server or virtual private server and it supports centOS, Red Hat Linux, and FreeBSD.

Application based support includes Apache, PHP, mySQL, Postgres, Perl, Python, and BIND. Email based support includes POP3, IMAP, SMTP services.