Plesk is a commercial web hosting panel that allows a server administrator to set up new websites, reseller accounts, e-mail accounts, and DNS entries through a web-based interface, without any specific systems administration knowledge.
A brief history of Plesk
Originally designed in Novosibirsk, Russia, the hosting automation software was released by Plesk Inc. and went live first in 2001. In 2003, Plesk was sold to SWSoft, which became Parallels in 2008. In December 2015 Plesk became a separate business entity, which has since been acquired by Oakley Capital.
Support for WordPress
Plesk provide an increasing amount of software administration support through their panel, in particular, support for WordPress has improved in recent versions, which is where Silicon Dales most often runs into Plesk: utilising the panel for clients who host multiple WP installs on dedicated servers, VPS or AWS EC2 clusters (which are also supported by Plesk).