Managing the source code for a software development project is only slightly less important than writing it in the first place. UNIX and Linux systems offer a rich selection of version control system (VCS) packages, each of which takes a slightly different approach to this common concern. This article focuses on the Mercurial source code management system, often simply referred to as hg. Mercurial provides a powerful, modern, and light-weight solution for source code control that makes it easy for developers to make and debug their changes to a software project while maintaining a stable, centralized source code repository that all project members can depend upon.