I've seen a lot of mention around the net about a lot of .NET Core targeting .NET Standard 1.6/2.0. With the release of .NET Core 2.1 today I'm curious what I would actually be able to get away with running on, let's say, a .NET Framework 4.7 website or application. How do I know what can and can't be used? I'm namely interested in knowing whether I'll ever be able to use the new SignalR in my existing WebAPI projects or if I'll have to completely transition over to Core to have any part in it.