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Because of the diversity of modern hardware and operating systems, many ways exist in which drivers can be used. Drivers are used for interfacing with:

• Printers
• Video adapters
• Network cards
• Sound cards
• Local buses of various sorts - in particular, for bus mastering on modern systems
• Low- bandwidth I/O buses of various sorts (for pointing deviceA pointing device is any hardware component that allows a user to input spatial data to a computer. CAD systems and Graphical User Interfaces (GUI) allow the user to control and provide data to the computer using physical "gestures" point, click, and drags such as miceA mouse is a handheld pointing device for computers, involving a small object fitted with one or more buttons and shaped to sit naturally under the hand. The underside of the mouse houses a device that detects the mouse's motion relative to the flat surfa, keyboardA computer keyboard is a peripheral modelled after the typewriter keyboard. Keyboards are designed for the input of written text, and also to control the operation of the computer. Physically, computer keyboards are an arrangement of rectangular or near-rs, USBNote: USB may also mean upper sideband in radio. Universal Serial Bus USB provides a serial bus standard for connecting devices, usually to a computer, but it also is in use on other devices such as set-top boxes, game consoles and PDAs. Overview A USB sy, etc.)
• Hard diskA hard disk (or hard disc or hard drive ) is a computer storage device. Mechanics A hard disk uses rigid rotating platters. It stores and retrieves digital data from a planar magnetic surface. Information is written to the disk by transmitting an electrom driveThe term drive has several common meanings: A form of computer storage, such as a hard drive . Driving the act of controlling a vehicle. Drive is an alternate name for motivation. A radio shift in the late afternoon is referred to as a drive time shift. buses ( ATAAdvanced Technology Attachment ATA , is a standard interface for connecting storage devices such as hard disk drives and CD-ROM drives inside personal computers. Many terms and synonyms for ATA exist, including abbreviations such as IDE ATAPI and UDMA ., SCSISCSI stands for Small Computer System Interface , and is a standard interface for transferring data between devices on a computer bus. SCSI is pronounced "scuzzy" when spoken aloud, while occasional attempts to promulgate the more flattering pronunciation)
• Implementing support for different file systems
• Implementing support for scanners and digital cameras

Common levels of abstraction for device drivers are:

• On the hardware side:
  • Interfacing directly
  • Using some higher-level interface (e.g. Video BIOS)
  • Using another lower-level device driver (e.g. file system drivers using disk drivers)
  • Simulating work with hardware, while doing something entirely different
• On the software side:
  • Allowing the operating system direct access to hardware resources
  • Implementing only primitives
  • Implementing an interface for non-driver software (e.g. TWAIN)
  • Implementing a language, sometimes quite high-level, e.g. PostScript

Writing a device driver is considered a challenge in most cases, as it requires an in-depth understanding of how a given platform functions, both at the hardware and the software level. In contrast to most types of user-level software running under modern operating systems, which can be stopped without greatly affecting the rest of the system, a bug in a device driver means in many cases that the whole system can stop functioning in a way which can severely damage the data or even the hardware of the computer system. Moreover, debugging device drivers is a difficult skill as it often involves monitoring hardware itself - which by definition behaves in a non-deterministic way.

All of this means that the people most likely to write device drivers come from the companies that develop the hardware - since they have more complete access to information about the design of their hardware than most outsiders. Moreover, it was traditionally considered in the hardware manufacturer's interest to guarantee that their clients would be able to use their hardware in an optimum way. However, in recent years non-vendors too have written numerous device drivers, mainly for use under free operating systems. In such cases, co-operation on behalf of the vendor is still important, however, as reverse engineering is much more difficult with hardware than it is with software, meaning it may take a long time to learn to operate hardware that has an unknown interface.