Really it's an article that talks a bit about the history of containers and how they differ from VMs. Essentially  a container reuses much of the host kernal and base system on Linux. On Windows, it uses most of the core Windows functionality, but provides some separation for applications. This is primarily to allow things like Java 8 and Java 9 to both exist in a single container, where they might not normally be allowed on the same OS host. Many types of applications struggle to have multiple versions of the app running at the same time. Containers allow separation.