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Common Misconceptions

Some common misconceptions about terminology.

It's not a "Docker container"

Docker is a company which develops container-related software. One of these software projects is the command-line docker program. The docker command-line program is used to create container images and run containers. However, it's only one such program which does so. Alternatives to docker include podman, apptainer, and Kubernetes. The vendor-neutral terms container image and container are preferred.

  • A container image is a static package which can be used to run software reproducibly.
  • A container is an instance of an image. A running container is what crunches numbers.

You build images and run containers.

Use Apptainer, Not Singularity

Singularity was an academic project. A for-profit company called Syslabs forked Singularity, taking its name, and commercialized it. To clear up the confusion, the original Singularity project was renamed to Apptainer.