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[[!meta title="What Is the GNU Hurd?"]]
The Hurd is the GNU project's replacement for [[UNIX]], a popular operating
The Hurd is firstly a collection of protocols formalizing how different
components may interact. The protocols are designed to reduce the mutual
[[trust]] requirements of the actors thereby permitting a more
[[extensible|extensibility]] system. These include interface definitions to
manipulate files and directories and to resolve path names. This allows any
process to implement a file system. The only requirement is that it have
access to its backing store and that the [[principal]] that started it own the
file system node to which it connects.
The Hurd is also a set of [[servers|translator]] that implement these
protocols. They include file systems, network protocols and authentication.
The servers run on top of the [[microkernel/Mach]] [[microkernel]] and use
Mach's [[microkernel/mach/IPC]] mechanism to transfer information.
The Hurd provides a compatibility layer such that compiling higher level
programs is essentially transparent; that is, by means of the [[glibc]], it
provides the same standard interfaces known from other [[UNIX]]-like systems.
Thus, for a typical user, the Hurd is intended to silently work in the
background providing the services and infrastructure which the [[microkernel]]
itself has no business implementing, but that are required for higher level
programs and libraries to operate.
The Hurd supplies the last major software component needed for a complete
[[GNU_operating_system|running/gnu]] as originally conceived by Richard
M. Stallman (RMS) in 1983. The GNU vision directly drove the creation and has
guided the evolution of the [Free Software Foundation](http://fsf.org/), the
organization that is the home of the [GNU project](http://gnu.org/gnu/).
The Hurd development effort is a somewhat separate project from the
Read about what the GNU Hurd is [[gramatically_speaking]].
Read about the [[origin_of_the_name]].