The Open Container Initiative (OCI) gave birth to the way we create containers today. It defined two specifications - the runtime-spec and the image-spec. In the previous article of the container series, we analyzed runc - an implementation of the OCI runtime-spec. In this article, we are going to study in detail the OCI image-spec. It defines how a runtime specification (hence a container) can be moved from one host to another. Furthermore, the specification provides means for OS resources to be efficiently shared between different container processes. The image-spec is implemented by Containerd and Docker which are considered as more "high-level" runtimes than runc. Let's dig into it!