In the bad old days of the Soviet Union, banned books and articles circulated in underground print editions.
Xeroxing was out; the secret police--no kidding--controlled access to copy machines.
So usually these "copies" were transcribed by hand or typed, and duplicated in this means by faithful readers, so that the population of copies in circulation grew as they made their way through their readership.
This practice of making and passing copies on clandestinely became known as samizdat (самиздат)-- literally, "self-published"--and some tremendously important works of fiction, nonfiction and poetry originally circulated in the USSR in this way.
Wikipedia notes: "With increased proliferation of computer technologies, it became practically impossible for the government to control the copying and distribution of samizdat."
And how. When average citizens own a machine that can be a printing press, a radio station, or a TV station depending on what software you download, control of information becomes impossible.
The only thing you can do, in a world of PCs, is to attempt to ruthlessly control access to the network, and this is what totalitarian states ranging from Saudi Arabia to China have attempted to do.
And, of course, Cuba... where it isn't working either:
A growing underground network of young people armed with computer memory sticks, digital cameras and clandestine Internet hookups has been mounting some challenges to the Cuban government in recent months, spreading news that the official state media try to suppress.Cyber-Rebels in Cuba Defy State's Limits (New York Times, 6 March 2008)
Last month, students at a prestigious computer science university videotaped an ugly confrontation they had with Ricardo Alarcón, the president of the National Assembly.
Mr. Alarcón seemed flummoxed when students grilled him on why they could not travel abroad, stay at hotels, earn better wages or use search engines like Google. The video spread like wildfire through Havana, passed from person to person, and seriously damaged Mr. Alarcón’s reputation in some circles.
Something similar happened in late January when officials tried to impose a tax on the tips and wages of employees of foreign companies. Workers erupted in jeers and shouts when told about the new tax, a moment caught on a cellphone camera and passed along by memory sticks.
“It passes from flash drive to flash drive,” said Ariel, 33, a computer programmer, who, like almost everyone else interviewed for this article, asked that his last name not be used for fear of political persecution. “This is going to get out of the government’s hands because the technology is moving so rapidly.”