ISO 216 is the international standard for paper sizes, and includes sizes such as A4, A3, etc. Here is a list some the A, B and C series sizes, and also some common US paper sizes.
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The history of paper
Modern paper is made from wood pulp, and the earliest examples of this is thought to have appeared in Han Dynasty China in the 2nd century BC.
Paper-like materials had been around in one form or another for thousands of years - the name derives from the Egyptian writing material papyrus. However it was the Chinese who first produced a material that we would recognise as what we call paper today.
Although paper spread throughout the East, gaining popularity in China and the Islamic world, it did not become widely used in Europe until the medievel period, around about the 13th century. Water-powered mills were introduced to produce the material, and an industry was born.
With the invention of the moveable type printing press by Johannes Gutenberg in the mid 15th century, paper gained even more importance. It is thought that 135 out of the estimated 180 copies of Gutenberg's Bible - the book printed with moveable type - were printed on paper with the remaining copies printed on vellum.
Newspapers followed in the early 17th century (news sheets had been introduced in China a few decades previously).
Even today with the internet and digital information readily available, paper consumption is still high. Between 1990 and 2002 consumption in the US rose to 90.7 million tons. The environmental impact of this demand has long been recognised, especially with its large contribution to deforestation. Now, many nations have targets concerning recycling. The US aims to recover 55% of paper used for recycling by 2012.