Two of the most important inventions in printing were movable metal type, which allowed words and paragraphs to be built up from individual metal blocks with letters on them, and the printing press. In Europe, these were both developed in the 1430s by the German goldsmith and inventor Johannes Gutenberg (1395–1468). Although born and brought up in Mainz, Gutenberg perfected his work on printing in Strasbourg. By 1448, Gutenberg had returned to Mainz, and his printing press was in full operation.

Movable type

Johannes Gutenberg's work on the printing press began in around 1436. It was Gutenberg's idea to split the text into individual letters (either lower or upper case) punctuation marks and other characters. The individual letters were each cast—as mirror images—in blocks of metal. The blocks were then assembled in a frame to form words, lines and pages. This is described as movable type: the blocks of type can be moved into countless different positions to print the text.

To produce the mould (also called a matrix), each letter was firstly cut into the face of a steel block, known as a punch. Careful steps were taken to ensure that all letters were of identical depth. A piece of type, or "sort", was then cast by filling the mould with molten metal, an alloy of lead, tin and antimony, which cooled and hardened.