A collection of Jazz charts, published without paying royalties and thus illegal (not in the Public Domain. ) For decades, a book called '1000 Standard Tunes' circulated; you can still see its grossly simplified charts, written three to a page. Some 25 years ago the "Real Book" appeared, out of the Berklee School of Music, with some 400 tunes in excellent calligraphy. This has become the standard and all Jazz musicians are expected to have a copy. More recently a number of legal fake books have been published. The best is The Ultimate Jazz Fakebook.