Containers are basic execution environments that are sandboxed and contained within sandboxed portions of an operating system. They are very useful for developing, testing and even deploying databases. See containers for details.
docker run -p 3306:3306 --name test-mysql -e MYSQL_ROOT_PASSWORD='root' -d mysqlp specifies the port mapping,
from the host port outside the container to the expected ports within the container.name specifies the name to refer to the container ase specifies environment variables to be accessible within the containerd specifies that the container should run detached,
as in not piping into the shell, running in backgroundmysql [name] the final specifier is the name of the container image to download,
in this case mysql