Docker is an application platform. It's a new way of running applications in isolated, lightweight units called containers. Containers are a very efficient way of running apps – much more efficient than virtual machines (VMs) or bare-metal servers. Containers start in seconds, and they don't add any overhead to the memory and compute requirements of an app. Docker is completely agnostic to the type of apps it can run. You can run a brand new .NET Core app in one container and a 10-year old ASP.NET 2.0 WebForms app in another container on the same server.
Containers are isolated units, but they can integrate with other components. Your WebForms container can access a REST API hosted in your .NET Core container. Your .NET Core container can access a SQL Server database running in a container, or a SQL Server instance running...