Container Linux by CoreOS, originally named CoreOS Linux, is an open source operating system (OS) that provides the functionality required to deploy and manage applications within containers.
Docker is an open source software platform to create, deploy and manage virtualized application containers on a common operating system (OS), with an ecosystem of allied tools.
Red Hat Atomic Host is a variant of the Red Hat Enterprise Linux supported, open source operating system, designed to be a minimal OS with optimizations for container hosting.
Ubuntu Core is a transactional version of the Ubuntu Linux OS, made specifically for internet of things (IoT) devices and large container deployments.
A unikernel is a library-based operating system that only includes functionalities required by the specific application that runs on it.