Docker Image:

is a layer of filesystem. like rootfs +userfs+ apps+ apps
all layers are read only.
layer wise we can create container.
when we pull the image then in var/lib/docker folder images is downloaded
when we create the container then in var/lib/docker folder merged layer is created with RW
file system conflict in layers then top layer is given priority.
when we stop the container then merged layer is removed
image is assigned to a user then a container is created
with inspect we can see the metadata of an image
with one image can create multiple container.
image can be pushed to a registery