Paper

Paper was invented in China somewhere between the 2nd century BC and the 2nd century AD, and eventually replaced such earlier writing media as papyrus (made from plants) and parchment (from animal skins). Paper is made from cellulose pulp, from wood (or other plant fibers) or rags.

Many forms of paper (especially the cheaper kinds) contain acid which eventually causes its deterioration, causing archival preservation difficulties. Archivists and collectors often use acid-free bags and boards to store paper documents and artifacts. Some paper items originally produced as ephemera have become rare and valuable collectibles, including comic books, trading cards, and postage stamps. For such items, preserving their original "mint condition" is considered highly important.

It can also be goat chow... as a bit of trivia, goats are able to digest cellulose fibers such as paper, making it nutritious to them in a way it is not for humans.