A dark Internet, dark address or Lost Net refers to any or all network hosts on the Internet that can no longer be accessed through conventional means. It is also called dark address space, Greynet or Sparce Darknets.
The dark Internet should not be confused with either deep web or darknet. Whereas deep web and darknet stand for hard-to-find websites and secretive networks that sometimes span across the Internet, they have a conventional mean to be accessed, when the dark Internet address is any portion of the Internet that can no longer be accessed through conventional means.
Failures within the allocation of Internet resources due to the Internet's chaotic tendencies of growth and decay are a leading cause of dark address formation. One form of dark address is military sites on the archaic MILNET. These government networks are sometimes as old as the original ARPANET, and have simply not been incorporated into the Internet's evolving architecture.