The people behind Washi Arts have a marvelous resource page giving all sorts of uses for washi paper – Click here.
On their “What is Washi” page they take you through the history, the materials, the methods of production and even the features of the paper – Click here.
They even have a classification list showing how the paper is graded – Click here.
In addition, check out this video showing washi paper in production:
A fascinating insight into a very traditional craft. It makes you value every sheet you use once you understand the laborious effort that goes into each piece.