Docker is the containerization platform that eliminates "works on my machine" problems. A Docker container packages the application code, runtime, system libraries, and configuration into an immutable image. The exact same image runs in dev, test, staging, and production — no environment drift, no missing dependencies, no configuration differences.
Enterprise Docker requires: multi-stage builds for optimized images (100MB not 2GB), Docker Compose for local development, container security scanning (Trivy, Snyk), image registry management (Azure Container Registry, Docker Hub), and CI/CD integration for automated build-push-deploy workflows.