Earthly is a tool designed to optimize CI/CD builds by addressing inefficiencies found in traditional pipelines through techniques like holistic layer caching and build graphs. It significantly speeds up builds, particularly in sandboxed CI environments, by reusing computations from previous runs, thereby reducing the redundancy of tasks like downloading dependencies and pulling container images. Earthly is most effective in complex build scenarios involving multiple interdependent projects, offering potential speed improvements ranging from 2 to 20 times faster than traditional methods. While it excels in CI builds, its benefits for local builds are more nuanced, depending on the complexity and context of the project. The tool's core value lies in reducing infrastructure costs and improving developer productivity by minimizing wait times and enabling faster feedback cycles, ultimately enhancing the overall velocity of feature delivery.