"GNU Hurd (usually referred to as the Hurd) is a free software computer operating system kernel, released under the GNU General Public License. It has been under development since 1990 by the GNU Project of the Free Software Foundation. It consists of a set of servers (or daemons, in Unix terminology) that work on top of a microkernel; together they form the kernel of GNU. The Hurd aims to surpass Unix kernels in functionality, security, and stability, while remaining largely compatible with them..."

The HURD was meant to be the true kernel at the heart of the GNU operating system. The promise behind the HURD was revolutionary – a set of daemons on top of a microkernel that was intended to surpass the performance of the monolithic kernels of traditional Unix systems and in doing so, give greater security, freedom and flexibility to the users – but it has yet to come down to earth.

"A Dutch university has landed a European Research Council grant to continue work on a Unix-type operating system that aims to be more reliable and secure than GNU/Linux or Microsoft Windows..." -- see also The GNU Hurd project

«Hurd having been in development for so long, but still not production-ready; and with Linux as a mature free kernel being firmly established as the de-facto standard kernel for the GNU system -- people often wonder: why haven't developers abandoned the Hurd long ago?

"David Chisnall takes a look at the GNU Project's infamous HURD kernel, exploring some of the features that make it unique and some that have found their way into other systems. [...] Even in its current state, HURD exists to prove a point: It’s possible to have a complete and usable system running nothing other than GNU code." -- http://www.informit.com/articles/printerfriendly.aspx?p=1180992

"...We make use of an installation script to install the GNU/Hurd system, which resides in the intial ramdisk having the base linux file system. The file system contains all the necessary binaries for the execution of the script...."

So what is the state of the Hurd? Is it vaporware, like Duke Nukem Forever? Fortunately not: the code exists, there is still work going on (for instance as part of Google Summer of Code), and there are even some relatively functional Hurd distributions. Let's look first at the code and the current architecture, and then at the Hurd distributions.

A month of the Hurd: Arch Hurd, updated Debian GNU/Hurd QEMU image, and GSoC students.

"A microkernel is a minimal computer operating system kernel which, in its purest form, provides no operating-system services at all, only the mechanisms needed to implement such services, such as low-level address space management, thread management, and inter-process communication (IPC).