Docker Architecture and explain all essential building blocks.

 The three main building blocks of docker are-

 a. Docker_Host (Docker Daemon, Images, containers)- A docker daemon or dockers is connected to API & is responsible for managing objects like - containers, volumes, networks mapping etc.

 b. Client (Responsible for ‘docker’ command line interface)- The ‘docker’ is used to carry out operations at client side by communicating to dockers via API calls. All commands like docker cp or docker run gets there result via dockers by API calls.  

c. Registry (For storing images)- All docker images whether its a base image or custom image is stored in dedicated repository known as docker registry. Commands like docker pull the image is pulled from registry. Using docker push command the image is inserted into registry.