In the below post I have tried to cover the basic terms which you will need to understand to start working with Docker. More information and reading refer to Docker Docs.
Docker -
The docker daemon process running on the host which manages images and containers. This is always referred to as Docker Engine.
Container -
Its a runtime instance of a docker image. Which consist of
Docker image
Execution environment
Set of instructions
Docker Hub -
The Docker Hub is a centralized repository with Docker and its components. Which consist of,
Docker image hosting
User authentication
Automated image builds and work-flow tools such as build triggers and web hooks
Integration with GitHub and Bitbucket
Dockerfile -
Docker images can be build using executing commands on the console. These set of commands can be executed sequentially by using the dockerfile.
A Dockerfile contains all the commands we execute manually in order to build a Docker image.
Base image -
A base image has no parent image specified in its Dockerfile. It is created using a Dockerfile with the FROM scratch directive.
Image -
Docker images are the basis of containers. An Image is an ordered collection of root filesystem changes and the corresponding execution parameters for use within a container runtime.
An image does not have a state and it never changes.
Filesystem -
A file system is a method an operating system uses to name files and assign them locations for efficient storage and retrieval.
Linux: ext4, aufs, btrfs, zfs
Windows: NTFS
macOS: HFS+
Persistent storage -
Persistent storage or volume storage provides a way for a user to add a persistent layer to the running container’s file system.
This persistent layer could live on the container host or an external device.
The lifecycle of this persistent layer is not connected to the lifecycle of the container, allowing a user to retain state.
Volume -
A volume is a specially-designated directory within one or more containers that bypasses the Union File System.
Volumes are designed to persist data, independent of the container’s life cycle. Docker therefore never automatically deletes volumes when you remove a container, nor will it “garbage collect” volumes that are no longer referenced by a container. Also known as data volume
There are three types of volumes: host, anonymous, and named:
A host volume lives on the Docker host’s filesystem and can be accessed from within the container.
A named volume is a volume which Docker manages where on disk the volume is created, but it is given a name.
An anonymous volume is similar to a named volume, however, it can be difficult, to refer to the same volume over time when it is an anonymous volume. Docker handle where the files are stored.
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