ASP.NET Core is a free, open-source, and cross-platform framework for building modern web applications. It was first released in 2016 and has since gone through several major updates, with the latest version being ASP.NET Core 7.0. This version was released in November 2021 and brings a number of new features and improvements to the framework. In this article, we will explore some of the key features and changes introduced in ASP.NET Core 7.0, along with beginner-friendly examples of how to use them in your own applications.

1 .NET MAUI (Multi-platform App UI)
One of the biggest changes in ASP.NET Core 7.0 is the inclusion of .NET MAUI (Multi-platform App UI), which is a new framework for building cross-platform applications with a single codebase. It allows developers to build applications for Windows, macOS, Linux, iOS, and Android using the same codebase and tools.

To build a cross-platform mobile application with .NET MAUI, you will need to install the latest version of Visual Studio or Visual Studio for Mac. Then, create a new .NET MAUI project and select the platforms you want to target (e.g. iOS, Android). You can then use XAML or razor syntax to design the user interface and C# to write the business logic.

Here is a simple example of how to use .NET MAUI to build a cross-platform mobile application that displays a list of items,
@using System.Collections.Generic

<StackLayout>
  <Label Text="Welcome to .NET MAUI!" />
  <ListView ItemsSource="@Items">
    <ListView.ItemTemplate>
      <DataTemplate>
        <TextCell Text="{Binding Name}" />
      </DataTemplate>
    </ListView.ItemTemplate>
  </ListView>
</StackLayout>

@code {
  public List<Item> Items { get; set; } = new List<Item>
  {
    new Item { Name = "Item 1" },
    new Item { Name = "Item 2" },
    new Item { Name = "Item 3" },
  };

  public class Item
  {
    public string Name { get; set; }
  }
}

2. Improved Blazor support
Blazor is a framework for building client-side web applications with C# and Razor syntax. In ASP.NET Core 7.0, Blazor has received several improvements, including support for native mobile apps, improved integration with server-side Blazor, and new features such as lazy loading and improved performance.

To use lazy loading in a Blazor application, you can use the new Lazy component. For example,
<Lazy Load="@LoadData">
  <Loading>Loading data...</Loading>
  <NotLoaded>Error loading data</NotLoaded>
  <Loaded>
    <table>
      <thead>
        <tr>
          <th>ID</th>
          <th>Name</th>
        </tr>
      </thead>
      <tbody>
        @foreach (var item in Data)
        {
          <tr>
            <td>@item.Id</td>
            <td>@item.Name</td>
          </tr>
        }
      </tbody>
    </table>

3. Enhanced performance and scalability
ASP.NET Core 7.0 has been optimized for performance and scalability, with improvements such as faster startup time, lower memory consumption, and better resource utilization. These improvements make it easier to build high-performance and scalable applications with ASP.NET Core.

4. New JSON APIs
ASP.NET Core 7.0 introduces several new JSON APIs, including JSON Text Sequences and JSON Lines, which allow developers to work with large JSON datasets more efficiently.

5. Improved security
ASP.NET Core 7.0 includes several security enhancements, including support for the latest security standards and protocols, such as TLS 1.3 and HTTP/3. It also includes new features such as certificate pinning, which helps protect against man-in-the-middle attacks.

ASP.NET Core 7.0 is a major release that introduces a number of new features and improvements. Some of the key highlights include support for ARM64, improved performance and scalability, support for C# 9 and F# 5, and support for HTTP/3. Additionally, ASP.NET Core 7.0 includes a number of new features and improvements to the Razor syntax, the Blazor framework, and the MVC framework. Overall, ASP.NET Core 7.0 is a significant update that offers a range of new capabilities for developers building web applications using the .NET platform.