A wildly brief overview, since the online docs and guides are incredibly good.
Docker is a tool to help us build and ship applications
Download / build Images
Create Containers based off of images
They’re not VMs
They’re not “lightweight VMs”
Google is your friend here
docker imageslists information about your imagesdocker psLists information about your containersdocker runRuns an imagedocker run docker/whalesay cowsay Howdyruns the whalesay imagedocker run -it busyboxruns the busybox image in interactive + pseudoterminal mode