If you’re a developer, you should be intimately familiar with Git. It’s the essential tool for software engineers, but is also hugely useful for just about anyone. Git is a version-controlling system for software and other text-based documents and files, which allows you to modify and make changes with a full history and branching system, among plenty of other great features (which are all explained elsewhere, far better than I ever could). If you’re a homelabber, Git can be great for managing your configurations.