Server 2016 introduces Nano Server, an edition of Windows Server which is even more cut down than Server Core. Nano Server is primarily designed as either a Hyper-V or Container host, or to be used in a VM running application workloads. The advantage of running a smaller operating system is that it boots faster, needs less servicing, and presents a smaller attach surface.
An obvious difference between Nano Server and other versions of Windows is that there is no command prompt and if you log on directly you see only a recovery console with a few basic settings. Nano Server must be managed remotely using PowerShell. Nano Server also supports only a subset of the Windows API. It runs Internet Information Server (IIS) but not the full .Net Framework, so ASP.Net applications must be written to target the cross-platform .Net Core framework. It can also run DNS and act as a storage host.