Blazor lets you build interactive web pages using C# instead of JavaScript. It runs on .NET, so if you already know C#, you can write both the front end and the back end of a web app in one language, sharing models and validation logic between them instead of maintaining two versions of the same idea.

Blazor comes in two hosting models, and the choice matters. Blazor WebAssembly runs your C# code in the browser itself, compiled to WebAssembly, so the app works as a single page application after the initial download. Blazor Server keeps the code on the server and sends only small UI updates to the browser over a live connection, which makes the first load fast but means every click round trips to the server. Many apps start with one model and switch later, because the component code stays mostly the same.

Components are the building block. A component is a Razor file that mixes HTML markup with C# code, and it re-renders itself when its state changes.…