An operating system (OS)
An operating system (OS) is a set of programs that control the execution of application programs and act as an intermediary between a user of a computer and the computer hardware. OS is software that manages the computer hardware as well as providing an environment for application programs to run. Examples of OS are: Windows, Windows/NT, OS/2 and MacOS.
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
STD ; Standard installation for those with own license key.
DLA ; Digital license activation (HWID).
OEM ; Will automatically activated if installing same version on original equipment.