A Brief History of screen printing.
Silkscreen printing has its origins in Japanese stencilling, but the screen printing process that we know today probably stems from the patents taken out by Samuel Simon of Manchester at the turn of the century. He used silk stretched on frames to support hand painted stencils, a process also used by William Morris. In 1914 John Pilsworth of San Francisco also took out a patent for multicolour printing, using the screen process.
During the First World War in America screen printing took off as an industrial printing process; it was mainly used at first for flags and banners but also for 'point of sale' advertising in the chain stores in America, which were appearing around that time.
Around this time the invention of the photographic stencil revolutionised the process; in the following years, obviously improvements were made in the presses, inks and chemicals used, but apart from the introduction of computer technology in the 1980's - in the pre-press side of screen printing - very little else has changed.
Artists have also used Silk screen printing, especially since the days of POP ART in the sixties - Andy Warhol, Rauschenberg and Hamilton are a few notorious examples. These artists opened up a whole new vista in the use of the screen process, leading also to the current cloth and T-shirt printing techniques in use today.
Excellent video tutorial