Docker multistage build short and simple explanation with command

A Docker multi-stage build is a technique that uses multiple FROM instructions in a single Dockerfile to create smaller, more secure, and efficient container images. The core idea is "build fat, ship thin": Stage 1 (The Build): Use a heavy image with all the compilers, tools, and source code needed to build your app. Stage 2 (The Runtime): Use a lightweight image and only copy the final compiled application (the artifact) from the first stage. Why use it? Smaller Size: Final images only contain what's needed to run, often reducing size by 90% or more (e.g., from 800MB to 20MB). Better Security: No compilers, source code, or extra packages are left in production, reducing the "attack surface". Simplicity: You manage everything in one file instead of separate build scripts. Simple Example (Go Application) This Dockerfile creates a tiny binary in the first stage and runs it in a minimal second stage. # STAGE 1: Build the app FROM golang:1.21-alpine AS builder WORKDIR /app COPY . . RUN go