In order to be able to answer this question, you have to know that there are

  • Docker images
  • Docker containers

Docker images are blueprints or templates.

Docker containers are the instances, created from the images.

docker create

creates a container from an image

docker start

starts a container

docker run

creates a container and starts it

note

Trying to use the run command twice results in something like…

docker: Error response from daemon: Conflict. The container name "/xxx" is already in use

bonus

docker run --rm

  • creates a container
  • runs it
  • deletes the container on exit

… which ensures you always run a fresh container.