docker image is a tar code example

Example: docker create image from tar file

$ docker image ls

REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE

$ docker load < busybox.tar.gz

Loaded image: busybox:latest
$ docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
busybox             latest              769b9341d937        7 weeks ago         2.489 MB

$ docker load --input fedora.tar

Loaded image: fedora:rawhide

Loaded image: fedora:20

$ docker images

REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
busybox             latest              769b9341d937        7 weeks ago         2.489 MB
fedora              rawhide             0d20aec6529d        7 weeks ago         387 MB
fedora              20                  58394af37342        7 weeks ago         385.5 MB
fedora              heisenbug           58394af37342        7 weeks ago         385.5 MB
fedora              latest              58394af37342        7 weeks ago         385.5 MB