Overview of Device Installation
The Windows operating system automatically installs devices without driver packages installed on them when those devices are reported to the operating system as present devices. This happens for all present devices when the system is booting and happens when a user plugs in (or manually installs) a Plug and Play (PnP) device. Drivers such as the ACPI driver and other PnP bus drivers help Windows determine which devices are present.
The following steps go over parts of this process in more detail: