Docker uses a client-server architecture. The Docker client talks to the Docker daemon, which does the heavy lifting of building, running, and distributing your Docker containers. The Docker client and daemon can run on the same system, or you can connect a Docker client to a remote Docker daemon. The Docker client and daemon communicate using a REST API, over UNIX sockets or a network interface. （Docker使用客户端 - 服务器架构。 Docker客户端与Docker守护进 程通信，后者负责构建，运行和分发Docker容器。 Docker客户端和守护程序可以在同一 系统上运行，也可以将Docker客户端连接到远程Docker守护程序。 Docker客户端和守 护程序使用REST API，通过UNIX套接字或网络接口进行通信。）
4.1 docker daemon
The Docker daemon ( dockerd ) listens for Docker API requests and manages Docker objects such as images, containers, networks, and volumes. A daemon can also communicate with other daemons to manage Docker services. (Docker守护程 序（dockerd）侦听Docker API请求并管理Docker对象，如图像，容器，网络和卷。 守 护程序还可以与其他守护程序通信以管理Docker服务。)
4.2 docker client
The Docker client ( docker ) is the primary way that many Docker users interact with Docker. When you use commands such as docker run , the client sends these commands to dockerd , which carries them out. The docker command uses the Docker API. The Docker client can communicate with more than one daemon. (Docker客户端（docker）是许多Docker用户与Docker交互的主要方式。 当您使用诸如 docker run之类的命令时，客户端会将这些命令发送到dockerd，后者将其执行。 docker命令使用Docker API。 Docker客户端可以与多个守护进程通信。)
4.3 docker registry
A Docker registry stores Docker images. Docker Hub is a public registry that anyone can use, and Docker is configured to look for images on Docker Hub by default. You can even run your own private registry. If you use Docker Datacenter (DDC), it includes Docker Trusted Registry (DTR). When you use the docker pull or docker run commands, the required images are pulled from your configured registry. When you use the docker push command, your image is pushed to your configured registry.(Docker注册表存储 Docker镜像。 Docker Hub是任何人都可以使用的公共注册中心，Docker配置为默认在 Docker Hub上查找图像。 您甚至可以运行自己的私人注册表。 如果您使用Docker Datacenter（DDC），它包括Docker Trusted Registry（DTR）。使用docker pull或 docker run命令时，将从配置的注册表中提取所需的映像。 使用docker push命令时， 图像将被推送到配置的注册表。)