# Architecture ### Docker Platform Docker provides the ability to package and run an application in a loosely isolated environment called a container. The isolation and security allow you to run many containers simultaneously on a given host. Containers are lightweight because they don’t need the extra load of a hypervisor, but run directly within the host machine’s kernel. ### Docker Engine *Docker Engine* is a client-server application with these major components: * A server which is a type of long-running program called a daemon process (the `dockerd` command). * A REST API which specifies interfaces that programs can use to talk to the daemon and instruct it what to do. * A command line interface (CLI) client (the `docker` command). ## Docker architecture 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. ### ![](https://4135025861-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-Lj1MxDg1HRVNIPUNVoQ%2F-Lj1N-c4E-QnQcM3XLzx%2F-Lj1NXwfhYE2iDusHOmU%2Fimport.png?generation=1562334343930640\&alt=media)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. ### Services Services allow you to scale containers across multiple Docker daemons, which all work together as a *swarm* with multiple *managers* and *workers*. Each member of a swarm is a Docker daemon, and the daemons all communicate using the Docker API. A service allows you to define the desired state, such as the number of replicas of the service that must be available at any given time.