Figure 6:

Version control systems (e.g., Git, Mercurial) work by storing incremental differences in files from 1 saved version (“commit”) to the next. To visualize the differences between each version, text editors such as Atom and online services such as GitHub, GitLab, and Bitbucket use red highlighting to denote deletions and green highlighting to denote additions. In this trivial example, a typographical error in version 1 (in pink) was corrected in version 2 (in green). These systems are extremely useful for code and manuscript development because it is possible to return to the snapshot of any saved version. This means that version control systems save you from accidental deletions, preserve code that you thought you no longer needed, and preserve a record of project changes over time.