Image vs container vs Dockerfile?

Definition:

A Docker image packages a filesystem and configuration for starting an application. A container is an isolated process environment created from an image with a writable layer and runtime settings. A Dockerfile describes how the image is built, making the package reproducible rather than depending on manual server setup.

Key points:

• An image is the packaged filesystem and configuration for an app.

• A container is an instance of that image; it may be running or stopped.

• A Dockerfile describes image build steps; containers share the host kernel.

• Containers share the host kernel; they are not full virtual machines with independent kernels.

Interview point:

• Distinguish build-time content from runtime configuration and persisted application data.