What is Blazor Server?

Blazor server or server-side Blazor runs on a web server inside ASP.NET Core and separates business logic from the UI. The UI is developed as an ASP.NET Core app and the backend code is hosted as Razor components on the server. UI updates from the server to the client-side are handled over a SignalR connection.
 
The Blazor Server runtime handles,
 
Sending UI events from the browser to the server.
 
Applying UI updates to the rendered component that are sent back by the server.
 
The connection used by Blazor Server to communicate with the browser is also used to handle JavaScript interop calls.