GNU Hurd (usually referred to as the Hurd or just Hurd) is the multiserver microkernel written as part of GNU. It has been under development since 1990 by the GNU Project of the Free Software Foundation, designed as a replacement for the Unix kernel, and released as free software under the GNU General Public License.GNU Hurd consists of a set of protocols and server processes (or daemons, in Unix terminology) that run on the GNU Mach microkernel.