An envelope is a way of packaging a product, it is usually made of flat, planar material such as paper or cardboard, designed to contain a flat object such as a letter or if you live in the UK a bill! Up until 1840 all envelopes were handmade, each taking some time to make, being individually cut to the appropriate shape of a rectangular sheet. In that year George Wilson in the U.K. patented the method of tessellating (tiling) a number of envelope patterns across and down a large sheet, reducing the amount of waste produced when making an envelope.