Johann Gutenberg’s invention of the printing press around 1448 had a significant impact on the spread of ideas in Europe and beyond. Printing technology traveled quickly across Europe and, at a time of great religious change, played a key role in the success of the Protestant Reformation. Reformation leader Martin Luther could only preach to a small number of people, but the printed word could spread his message to thousands more
The printing press drastically cut the cost of producing books and other printed materials. Prior to Gutenberg’s invention, the only way of making multiple copies of a book was to copy the text by hand, an laborious and intensely time-consuming occupation usually performed by monks. The materials involved were also costly: Monks wrote on treated skins, known as vellum, and a single copy of the Bible could require 300 sheepskins or 170 calfskins. Printing onto paper made copying cheaper and faster.
My source:
http://classroom.synonym.com/impact-did-invention-printing-press-spread-religion-6617.html
It's the former practice of segregating black people in the US.
