Book Binding
When shopping for books (online especially), one often encounters various binding styles - Hardcover, Paperback, Mass Market, and Trade. I found a webpage that does a good job of explaining the differences between them. Hardcover and paperback are straightforward, but the latter two less so. Trade is high quality, often the first run of a book (often hardcover), and mass market is a cheaper, later run (often paperback).
AddAll explains it as such:
Mass Market: A smaller paperback, the size you often find at grocery store.
Trade Paperback: Usually taller, wider, and printed on nicer paper than a mass market.