Mac OS X Server (later called OS X Server and macOS Server), is a discontinued series of Unix-like server operating systems developed by Apple Inc. based on macOS. It provided server functionality and system administration tools, and provided tools to manage both macOS-based computers and iOS-based devices. Versions of Mac OS X Server prior to version 10.7 “Lion” were sold as complete, standalone server operating systems; starting with Mac OS X 10.7 “Lion,” Mac OS X Server (and its successors OS X Server and macOS Server) have been offered as add-on software packages, sold through the Mac App Store, that are installed on top of a corresponding macOS installation. macOS Server at one point provided network services such as a mail transfer agent, AFP and SMB servers, an LDAP server, and a domain name server, as well as server applications including a Web server, database, and calendar server. The latest version of macOS server only includes functionality related to user and group management, Xsan, and mobile device management through profiles. On April 21, 2022, Apple announced it would be discontinuing macOS Server and that future versions of macOS would drop support for it. Overview Mac OS X Server was provided as the operating system for Xserve computers, rack mounted server computers designed by Apple. Also, it was optionally pre-installed on the Mac Mini and Mac Pro and was sold separately for use on any Macintosh computer meeting its minimum requirements. macOS Server versions prior to Lion are based on an open source foundation called Darwin and use open industry standards and protocols. History Mac OS X Server 1.0 (Rhapsody) Mac OS X Server 1.0 was released in March 1999, predating the release of the consumer version of Mac OS X by two years. Mac OS X Server 1.0 was based on Rhapsody, a hybrid of OPENSTEP from NeXT Computer and Mac OS 8.5.1. The GUI looked like a mixture of Mac OS 8's Platinum appearance with OPENSTEP's NeXT-based interface. It included a runtime layer called Blue Box for running legacy Mac OS-based applications within a separate window. There was discussion of implementing a 'transparent blue box' which would intermix Mac OS applications with those written for Rhapsody's Yellow Box environment, but this would not happen until Mac OS X's Classic environment. Apple File Services, Macintosh Manager, QuickTime Streaming Server, WebObjects, and NetBoot were included with Mac OS X Server 1.0.