What Does Rackmount Server Mean?
A rackmount server is a type of hardware that is placed in a downright horizontal rack, rather than in an upright tower server system. It provides the ability to install more than one server within a single rack-mount server chassis or casing.
Techopedia Explains Rackmount Server
Rackmount servers collectively host, execute and manage an enterprise application or serve as a data center. Designed to save physical floor space and other server resources, a rackmount server is typically housed with a horizontal rack chassis that can simultaneously hold multiple servers placed above each other.