image in docker code example

Example 1: docker images

docker images

Example 2: docker image

what is container? 
Basically docker is a super light-weight
Virtual machine which has all necessery
programs and dependencies in order to run
your program. When we setup big application
which has UI, database, and lots of
microservices we need to do a setup and
each of this services need some kind of program
to work like JAVA and so on. And to setup
everything and installing correctly in the
new server probably would take days.
But most of the time versions are not matching
and other problems so you need to debug it
which is very time consuming. So what dockers
is doing, we create image and we are explaining
what exactly is needed for our program. 
So basically we are saying these are the dependencies,
this is our program where it's coming from and
than we we need to create a container with
our program we just pulling from Docker registry.
And container with a program will be running and
it can be bootsrap in few seconds. So we just
download and start in few seconds and
whoever will be requesting that image will
have exactly same setup. Biggest advantage of
dockers is to ability to have exactly same
setup everywhere and also you can very quickly
bootstrap the whole infrastructure.
And containers can build very quickly.