Samizdat: Censorship and self publishing in the USSR

Samizdat was the clandestine copying and distribution of government-suppressed literature or other media in Soviet-bloc countries. Copies were made a few at a time, and those who received a copy would be expected to make more copies. This was often done by handwriting or typing. This grassroots practice to evade officially imposed censorship was fraught with danger as harsh punishments were meted out to people caught possessing or copying censored materials.

Wikipedia entry on Samizdat

Another piece on Samizdat can be found here:
Samizdat – a brief history