Multi-stage builds keep images small

Multi-stage builds use multiple FROM statements in a single Dockerfile; each FROM can use a different base and begins a new stage of the build. You selectively copy artifacts from one stage into another with COPY --from, leaving behind everything you don't want in the final image, so the end result can be a tiny production image containing only the built binary with none of the build tools required to build it. Name stages with FROM <image> AS <name> and refer to the name in COPY --from so the copy doesn't break if instructions are reordered later; unnamed stages are referenced by integer index starting at 0 for the first FROM. You can stop at a specific build stage with docker build --target <name>, useful for keeping a debug stage with debugging symbols or tools alongside a lean production stage, and BuildKit only builds the stages that the target stage depends on. COPY --from can also copy artifacts from a separate image by local image name, a tag available locally or on a registry, or a tag ID, pulling the image if necessary. Scope: Dockerfile builds with BuildKit. Reviewed October 4, 2026.