In C#, an anonymous class is a temporary class with no explicitly defined type. Anonymous classes are typically used for creating temporary data structures without explicitly defining a new class.

The instructions for use are as follows:

// 创建一个匿名类
var person = new { Name = "John", Age = 30 };

// 访问匿名类的属性
Console.WriteLine($"Name: {person.Name}, Age: {person.Age}");

// 匿名类可以作为方法的返回类型
var person = new Func<object>(() => new { Name = "John", Age = 30 })();
Console.WriteLine($"Name: {person.Name}, Age: {person.Age}");

It is important to note that anonymous classes are read-only, meaning that their property values cannot be modified. Additionally, anonymous classes can only be used within a local scope and cannot be used as a class member or method parameter.