What is Docker?

What Docker Solves

Docker packages an application together with the files, libraries, runtime, and configuration it needs into a portable unit called a container. This reduces the classic problem where an application works on one computer but fails on another because environments differ.

A container is not a lightweight virtual machine. Containers share the host kernel while isolating processes, filesystems, networks, and other resources. Docker images are immutable templates from which containers are created.

Docker Vocabulary

• Image: a read-only package used to create containers.
• Container: a running or stopped instance of an image.
• Registry: a service that stores and distributes images.
• Dockerfile: instructions used to build an image.
• Volume: persistent storage managed separately from a container's writable layer.