macOS, originally Mac OS X, previously shortened as OS X, is an operating system developed and marketed by Apple since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and laptop computers, it is the second most widely used desktop OS, after Microsoft Windows and ahead of all Linux distributions, including ChromeOS.
Mac OS X Server is a series of discontinued Unix-like server operating systems developed by Apple Inc. based on macOS. It provided server functionality and system administration tools, and tools to manage both macOS-based computers and iOS-based devices, 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.
Disk partitioning or disk slicing is the creation of one or more regions on secondary storage, so that each region can be managed separately. These regions are called partitions. It is typically the first step of preparing a newly installed disk, before any file system is created. The disk stores the information about the partitions' locations and sizes in an area known as the partition table that the operating system reads before any other part of the disk. Each partition then appears to the operating system as a distinct "logical" disk that uses part of the actual disk. System administrators use a program called a partition editor to create, resize, delete, and manipulate the partitions. Partitioning allows the use of different filesystems to be installed for different kinds of files. Separating user data from system data can prevent the system partition from becoming full and rendering the system unusable. Partitioning can also make backing up easier. A disadvantage is that it can be difficult to properly size partitions, resulting in having one partition with too much free space and another nearly totally allocated.
The history of macOS, Apple's current Mac operating system formerly named Mac OS X until 2011 and then OS X until 2016, began with the company's project to replace its "classic" Mac OS. That system, up to and including its final release Mac OS 9, was a direct descendant of the operating system Apple had used in its Mac computers since their introduction in 1984. However, the current macOS is a UNIX operating system built on technology that had been developed at NeXT from the 1980s until Apple purchased the company in early 1997.
FileVault is a disk encryption program in Mac OS X 10.3 Panther (2003) and later. It performs on-the-fly encryption with volumes on Mac computers.
Multi-booting is the act of installing multiple operating systems on a single computer, and being able to choose which one to boot. The term dual-booting refers to the common configuration of specifically two operating systems. Multi-booting may require a custom boot loader.
Unified Extensible Firmware Interface is a specification that defines the architecture of the platform firmware used for booting the computer hardware and its interface for interaction with the operating system. Examples of firmware that implement the specification are AMI Aptio, Phoenix SecureCore, TianoCore EDK II, InsydeH2O. UEFI replaces the BIOS which was present in the boot ROM of all personal computers that are IBM PC compatible, although it can provide backwards compatibility with the BIOS using CSM booting. Intel developed the original Extensible Firmware Interface (EFI) specification. Some of the EFI's practices and data formats mirror those of Microsoft Windows. In 2005, UEFI deprecated EFI 1.10.
HFS Plus or HFS+ is a journaling file system developed by Apple Inc. It replaced the Hierarchical File System (HFS) as the primary file system of Apple computers with the 1998 release of Mac OS 8.1. HFS+ continued as the primary Mac OS X file system until it was itself replaced with the Apple File System (APFS), released with macOS High Sierra in 2017. HFS+ is also one of the formats supported by the iPod digital music player.
Mac OS X Leopard is the sixth major release of macOS, Apple's desktop and server operating system for Macintosh computers. Leopard was released on October 26, 2007 as the successor of Mac OS X Tiger, and is available in two editions: a desktop version suitable for personal computers, and a server version, Mac OS X Server. It retailed for $129 for the desktop version and $499 for Server. Leopard was superseded by Mac OS X Snow Leopard in 2009. Mac OS X Leopard is the last version of macOS that supports the PowerPC architecture as its successor, Mac OS X Snow Leopard, functions solely on Intel based Macs.
A Hackintosh is a computer that runs Apple's Macintosh operating system macOS on computer hardware that is not authorized for the purpose by Apple. This can also include running Macintosh software on hardware it is not originally authorized for. Benefits of "Hackintoshing" can include cost, ease of repair and piecemeal upgrade, and freedom to use customized choices of components that are not available in the branded Apple products. macOS can also be run on several non-Apple virtualization platforms, although such systems are not usually described as Hackintoshes. Hackintosh laptops are sometimes referred to as "Hackbooks".
The GUID Partition Table (GPT) is a standard for the layout of partition tables of a physical computer storage device, such as a hard disk drive or solid-state drive, using universally unique identifiers (UUIDs), which are also known as globally unique identifiers (GUIDs). Forming a part of the Unified Extensible Firmware Interface (UEFI) standard, it is nevertheless also used for some BIOSs, because of the limitations of master boot record (MBR) partition tables, which use 32 bits for logical block addressing (LBA) of traditional 512-byte disk sectors.
The Apple–Intel architecture, or Mactel, is an unofficial name used for Macintosh personal computers developed and manufactured by Apple Inc. that use Intel x86 processors, rather than the PowerPC and Motorola 68000 ("68k") series processors used in their predecessors or the ARM-based Apple silicon SoCs used in their successors. As Apple changed the architecture of its products, they changed the firmware from the Open Firmware used on PowerPC-based Macs to the Intel-designed Extensible Firmware Interface (EFI). With the change in processor architecture to x86, Macs gained the ability to boot into x86-native operating systems, while Intel VT-x brought near-native virtualization with macOS as the host OS.
Apple Partition Map (APM) is a partition scheme used to define the low-level organization of data on disks formatted for use with 68k and PowerPC Macintosh computers. It was introduced with the Macintosh II.
Mac Pro is a series of workstations and servers for professionals made by Apple Inc. since 2006. The Mac Pro, by some performance benchmarks, is the most powerful computer that Apple offers. It is one of four desktop computers in the current Mac lineup, sitting above the Mac Mini, iMac and Mac Studio.
A live USB is a portable USB-attached external data storage device containing a full operating system that can be booted from. The term is reminiscent of USB flash drives but may encompass an external hard disk drive or solid-state drive, though they may be referred to as "live HDD" and "live SSD" respectively. They are the evolutionary next step after live CDs, but with the added benefit of writable storage, allowing customizations to the booted operating system. Live USBs can be used in embedded systems for system administration, data recovery, or test driving, and can persistently save settings and install software packages on the USB device.
The EFIsystem partition or ESP is a partition on a data storage device that is used by computers that have the Unified Extensible Firmware Interface (UEFI). When a computer is booted, UEFI firmware loads files stored on the ESP to start operating systems and various utilities.
Parallels Desktop for Mac is software providing hardware virtualization for Macintosh computers with Intel processors, and since version 16.5 also for Apple silicon-based Macintosh computers. It is developed by Parallels, since 2018 a subsidiary of Corel.
Oracle VM VirtualBox is a hosted hypervisor for x86 virtualization developed by Oracle Corporation. VirtualBox was originally created by InnoTek Systemberatung GmbH, which was acquired by Sun Microsystems in 2008, which was in turn acquired by Oracle in 2010.
Mac OS X Snow Leopard is the seventh major release of macOS, Apple's desktop and server operating system for Macintosh computers.
OS X Lion, also known as Mac OS X Lion, is the eighth major release of macOS, Apple's desktop and server operating system for Mac computers.
(29 August 2022) 
