Ryan Tomayko's "The Thing About Git" is a resourceful post that delves into advanced Git usage, covering practical techniques such as adding changes to a previous commit, committing only part of a changed file, and altering the message of an older commit. Written by Chris Wanstrath, also known as @defunkt, it invites readers to contribute their own Git tricks to the guide, enhancing its utility and collaborative value for users seeking to deepen their understanding and mastery of Git.