What is a Docker image?

A Docker image is indeed a lightweight, stand-alone package for running software. This package contains everything needed to run an application, including the code, runtime, libraries, and dependencies. By encapsulating all components required to execute the application, Docker images ensure that the software runs consistently across different environments, regardless of the underlying operating system differences or configurations.

When a Docker image is created, it's designed as a blueprint for containers, which are the executable instances of the images. Since Docker images are immutable, they can be shared, versioned, and stored effectively, allowing developers to collaborate more easily and maintain a consistent application deployment.

This option highlights the fundamental purpose and functionality of Docker images in isolating applications in containers, enhancing portability and efficiency in application development and deployment. Understanding this concept is crucial for effectively utilizing Docker technologies in software development and operations.