The Cathedral and the Bazaar (abbreviated CatB) is an essay by Eric S. Raymond on software engineering methods, based on his observations of the Linux kernel development process and his experiences managing an open source project, fetchmail. It examines the struggle between top-down and bottom-up design. It was first presented by the author at the Linux Kongress on May 27, 1997 in Würzburg and was published as part of a book of the same name in 1999.