<publication> (Russian, literally "self publishing") The process of disseminating documentation via underground channels. Originally referred to photocopy duplication and distribution of banned books in the former Soviet Union; now refers by obvious extension to any less-than-official promulgation of textual material, especially rare, obsolete, or never-formally-published computer documentation. Samizdat is obviously much easier when one has access to high-bandwidth networks and high-quality laser printers.
Strictly, "samizdat" only applies to distribution of needed documents that are otherwise unavailable, and not to duplication of material that is available for sale under copyright.
See Lions Book for a historical example.
See also: hacker ethic.