Explain the Docker architecture and its main components.

Docker architecture consists of: 1) Docker Client: Command-line interface that communicates with Docker daemon, 2) Docker Daemon (dockerd): Background service that manages containers, images, networks, 3) Docker Images: Read-only templates used to create containers, 4) Docker Containers: Running instances of Docker images, 5) Docker Registry: Storage for Docker images (Docker Hub, private registries), 6) Docker Engine: Runtime that creates and manages containers. Example workflow: docker run nginx - Client sends command to daemon, Daemon pulls nginx image from registry, Daemon creates and starts container.