DC's Piranha Press and other imprints (including the mature readers line Vertigo, and Helix, a short-lived science fiction imprint) were introduced to facilitate compartmentalized diversification and allow for specialized marketing of individual product lines. They increased the use of non-traditional contractual arrangements, including the dramatic rise of creator-owned projects, leading to a significant increase in critically lauded work (much of it for Vertigo) and the licensing of material from other companies. DC also increased publication of book-store friendly formats, including trade paperback collections of individual serial comics, as well as original graphic novels.