Firmin Didot was a French printer, engraver, and type founder. He invented the word "stereotype", which in printing refers to the metal printing plate created for the actual printing of pages (as opposed to printing pages directly with movable type), and used the process extensively, revolutionizing the book trade by his cheap editions. His manufactory was a place of pilgrimage for the printers of the world.
Firmin Didot was born in Paris into a family of printers founded by François Didot, the father of 11 children. Firmin was one of his grandchildren. The family's paper manufactory was located at Essonnes, a town c. 30 km southeast of Paris near Corbeil, which had notable paper factories.
France is indebted to the Didot family for the publication of the Biographie Nationale, and Belgium is also indebted for the establishment of her Royal Press. Relatives of Firmin Didot include François Ambroise Didot (1730–1804); Pierre François Didot (1732–95); Henri Didot (1765–1862); and Pierre Didot (1760–1853).
Along with Giambattista Bodoni of Italy, Firmin Didot is credited with establishing the use of the "Modern" classification of typefaces. The types that Didot used are characterized by extreme contrast in thick strokes and thin strokes, by the use of hairline serifs and by the vertical stress of the letters. Many fonts today are available based on Firmin Didot's typefaces. These include Linotype Didot and HTF Didot.