A filter driver is a Microsoft Windows

Microsoft Windows

Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

 driver that adds value to peripheral devices or supports a specialized device in the personal computer

Personal computer

A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...

. It is a driver/program/module that is inserted into the existing driver stack to perform some specific function. A filter driver should not affect the normal working of the existing driver stack in any major way. Written either by Microsoft

Microsoft

Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...

 or the vendor of the hardware

Computer hardware

Personal computer hardware are component devices which are typically installed into or peripheral to a computer case to create a personal computer upon which system software is installed including a firmware interface such as a BIOS and an operating system which supports application software that...

, any number of filter drivers can be added to Windows. Upper level filter drivers sit above the primary driver for the device (the function driver), while lower level filter drivers sit below the function driver and above the bus

Computer bus

In computer architecture, a bus is a subsystem that transfers data between components inside a computer, or between computers.Early computer buses were literally parallel electrical wires with multiple connections, but the term is now used for any physical arrangement that provides the same...

 driver.

Filters may work on a certain brand of device such as a mouse

Mouse (computing)

In computing, a mouse is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. Physically, a mouse consists of an object held under one of the user's hands, with one or more buttons...

 or keyboard

Computer keyboard

In computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...

, or they may perform some operation on a class of devices, such as any mouse or any keyboard. Another type of filter driver is the bus filter driver, which may be added on top of the bus driver. For example, an ACPI

Advanced Configuration and Power Interface

In computing, the Advanced Configuration and Power Interface specification provides an open standard for device configuration and power management by the operating system....

 bus filter is added to support power management

Power management

Power management is a feature of some electrical appliances, especially copiers, computers and computer peripherals such as monitors and printers, that turns off the power or switches the system to a low-power state when inactive. In computing this is known as PC power management and is built...

 for each device.

See also

• Windows Driver Model
  Windows Driver Model
  In computing, the Windows Driver Model — also known at one point as the Win32 Driver Model — is a framework for device drivers that was introduced with Windows 98 and Windows 2000 to replace VxD, which was used on older versions of Windows such as Windows 95 and Windows 3.1, as well...
  
  
• Device Driver
  Device driver
  In computing, a device driver or software driver is a computer program allowing higher-level computer programs to interact with a hardware device....
  
  
• Advanced Configuration and Power Interface
  Advanced Configuration and Power Interface
  In computing, the Advanced Configuration and Power Interface specification provides an open standard for device configuration and power management by the operating system....