Plesk (ex: Parallels Plesk Control Panel, Plesk Server Administrator, or just Plesk) is a commercial web hosting automation program sold by Oding.
Off Topic Warning:
The majority of questions regarding the Plesk control panel are likely to be closed as they are not considered on-topic for ServerFault:
Questions involving web hosting control panels are off-topic at Server Fault because they customize their systems such that normal administration tools and methods no longer apply, and thus require support from the vendor or the web hosting industry. See Where can I ask questions about web hosting control panels?