Scott Chacon's "Git Internals" PDF, published by Peepcode, is a comprehensive guide for those interested in understanding the deeper mechanics of Git beyond the standard commands. The document not only delves into the technical details of Git's inner workings but also provides insights into its daily use, workflows, and best practices. Regardless of one's familiarity with Git, readers are likely to discover new knowledge or techniques within its pages. The PDF is authored by Chris Wanstrath, also known by his handle @defunkt.