The word ukiyo refers to the world of common people and e means "picture." Thus when ukiyo-e first emerged in the late sixteenth century, it usually depicted everyday life in the city of Kyoto. It wasn't until the eighteenth century that ukiyo-e became a popular art form, though, thanks partly to advances in woodblock printing techniques. Also, familiar subjects like kabuki actors and beautiful women came to be depicted around this time, and books carrying illustrations by young ukiyo-e artists were widely circulated. These factors helped ukiyo-e become a part of Japan's popular culture.
At first ukiyo-e weren't prints but paintings made with sumi(black ink); later on, color was added, and as the number of colors increased and the paintings became more complicated, the woodblock printing technique was developed to mass-produce prints of the same design. Only a few colors were used in the early prints, but as the technique improved, ukiyo-e became more colorful and refined.
Making woodblock prints was a three-stage process: (1) painting a design with ink, (2) carving the design onto wooden blocks, and (3) applying colored ink to the blocks and pressing sheets of paper on them to print the design. There were specialists for each of these stages, and the entire process took a lot of work, but once the blocks were completed, it became much easier than before to make reproductions of the same design.
The prints mass-produced in this way were circulated widely among the public, and ukiyo-e developed into a popular art form.
As ukiyo-e developed into popular art, subjects having to do with entertainment came to be taken up. Yakusha-e were portraits of kabuki actors in popular roles; they were sort of like the posters and photographs of movie stars that you can get today. Bijin-ga illustrated beautiful women of Edo (present-day Tokyo)
You can think of them as images of the ideal urban woman. Landscapes didn't become the subjects of ukiyo-e until later, when people became better off and could go on trips for leisure. Landscape prints were used as today's equivalent of postcards.
At around the end of the nineteenth century, European painters came across ukiyo-e prints that were being used as wrapping paper. They were struck very strongly by the expressive curves, bold use of colors, and liberal designs of ukiyo-e.
Until then, European and U.S. artists had never come across the sorts of techniques that ukiyo-e artists used. Ukiyo-e thus had a great influence on such Impressionist painters as Vincent van Gogh and Claude Monet.
Photos (from top): Mikaeri Bijin (A Beauty Looking over Her Shoulder) by Hishikawa Moronobu; Ichikawa Monnosuke (The Actor Ichikawa Monnosuke) by Torii Kiyonobu; Tokaido Gojusantsugi: Yokkaichi (Fifty-Three Stations of the Tokaido: Yokkaichi) by Utagawa Hiroshige; Sawamura Sojuro (The Actor Sawamura Sojuro) by Utagawa Toyokuni; Furyu Rokkasen: Sojo Henjo (Six Famous Poets: The Priest Henjo) by Suzuki Harunobu. (Courtesy of the Tokyo National Museum)