Pomerantz explains what metadata is, and why it exists. He distinguishes among different types of metadata -- descriptive, administrative, structural, preservation, and use -- and examines different users and uses of each type. He discusses the technologies that make modern metadata possible, and he speculates about metadata's future. By the end of the book, readers will see metadata everywhere. Because, Pomerantz warns us, it's metadata's world, and we are just living in it.