Define a Docker container.

A Docker container is best defined as a lightweight, standalone, executable package that includes everything needed to run a piece of software, including the code, runtime, libraries, and system tools. This definition highlights the key characteristics of Docker containers: they are designed to be portable and consistent across various computing environments, which is a significant advantage over traditional virtual machines.

By being lightweight, Docker containers share the host operating system's kernel, which allows them to use fewer resources than virtual machines that require their separate operating system and may include more overhead. This means that multiple containers can run simultaneously without significantly taxing the host system. Furthermore, containers remain isolated from each other, ensuring that dependencies and configurations do not conflict, allowing for streamlined development and deployment processes.

This concept of a standalone package means that applications can be packaged with their dependencies and run reliably irrespective of where the environment is—be it on a developer’s laptop, in an organization's data center, or in the cloud. The emphasis on executability signifies that containers facilitate quick and efficient deployment of applications, which is a cornerstone of modern software development practices such as Continuous Integration and Continuous Deployment (CI/CD).

Hence, defining a Docker container as a lightweight, standalone, executable package encompasses its core functionality and advantages within the ecosystem