Docker layer caching is a technique that significantly enhances the efficiency of Docker image builds by reusing previously built layers, which can notably reduce build times, particularly in Continuous Integration (CI) environments that are designed to be ephemeral. This method requires developers to manage cloud storage buckets for storing cached layers between pipeline executions and to modify Docker build commands appropriately. In environments like Harness CI Cloud, enabling Docker layer caching is simplified to a single checkbox in the Docker image build step, as demonstrated by a reduction in the build time of a Grafana Docker image from seven minutes to just twenty seconds. Dockerfiles, which consist of a sequence of instructions, are central to this process; rearranging these instructions from least to most frequently changed can optimize layer caching, thus minimizing unnecessary rebuilds and saving developer time. Docker's caching mechanism operates by rebuilding all subsequent layers if a preceding layer changes, making strategic ordering crucial to efficiency. For those interested in maximizing the benefits of Docker layer caching, resources like Docker’s official documentation on cache management offer valuable guidance, and Harness provides additional tools like Test Intelligence and Cache Intelligence to further accelerate pipeline performance.