Mac OS X Server is Apple's UNIX server operating system. Based on the same architecture as Mac OS X, Mac OS X Server includes additional services, applications and administration tools for managing and deploying servers.
Mac OS X Server is the operating system included on Xserve, Apple's 1U rack mount server. Mac OS X Server is also sold separately for use on Apple desktop computers including Mac Pro, iMac and Mac mini. Mac OS X Server is commonly found in small business, education and large enterprise organizations.