What is the purpose of multi-stage builds?

While multi-stage builds can improve the logical organization of a Dockerfile, their main purpose is not just readability but concrete image optimization.

Multi-stage builds optimize images by allowing the separation of build-time dependencies from runtime dependencies. Only the necessary artifacts, such as compiled binaries, are copied from an earlier build stage to the final production image, discarding build tools and intermediate files and significantly reducing the final image size.

Although caching is leveraged during multi-stage builds, it's a general Docker build feature; the primary purpose of multi-stage builds is not better caching, but image size reduction through artifact selection.

Multi-stage builds execute stages sequentially; they do not inherently allow for parallel execution of Docker builds, which would typically require separate build processes.