How do Razor components (.razor files) combine markup and C# code, and what is the @code block?

A .razor component file mixes HTML-like markup with embedded C# expressions (using @ syntax) for data binding and control flow, plus an @code block containing the component's C# class members (properties, fields, methods, lifecycle overrides) -- Blazor compiles this into a regular C# class at build time, with the markup becoming a BuildRenderTree method.

<h3>@Title</h3>
<button @onclick="IncrementCount">Count: @count</button>

@code {
    [Parameter] public string Title { get; set; } = "Counter";
    private int count = 0;
    private void IncrementCount() => count++;
}