operating systems kernels

The kernel is the central part of an operating system, that directly controls the computer hardware. Usually, the kernel is the first of the user-installed software on a computer, booting directly after the BIOS. Operating system kernels are specific to the hardware on which they are running, thus most operating systems are distributed with different kernel options that are configured when the system is installed. Changing major hardware components such as the motherboard, processor, or memory, often requires a kernel update. Additionally, often new kernels are offered that improve system security or performance. The two major types of kernels competing in today's computer markets are the Windows kernel and the unix-like kernels.

There are three broad categories of kernels :

Monolithic kernels provide rich and powerful abstractions of the underlying hardware.

Microkernels provide a small set of simple hardware abstractions and use applications called servers to provide more functionality.

Exokernels provide no abstractions but allow the use of libraries to provide more functionality via direct or nearly direct access to hardware.

The Windows kernel is available only with the Microsoft Windows series of operating systems. It is proprietary software, developed and distributed by Microsoft Corporation. Introduced in Windows/386, it's many incarnations have since gone by several different names, and some had no names at all. The latest version of the Windows kernel was introduced in Windows NT, and has had many of it's functions removed and placed in user-mode software for Windows Vista. This leads to increased system stability and security. In Vista, application-level software exploits have much less access to the core functions of the operating system, and application crashes will not bring down the OS.