C# :: Use Of Auto-implemented Properties?

Code using auto-implemented property:

public class MyClass {
public int age { get; set; }
}
static void Main(string[] args) {
MyClass testing = new MyClass();
testing.age = 44;
Console.WriteLine(testing.age);
}

output: 44

Code using regular variable declaration:

public class MyClass {
public int age;
}
static void Main(string[] args) {
MyClass testing = new MyClass();
testing.age = 44;
Console.WriteLine(testing.age);
}

output: 44

Why use the auto-implemented property when you can just as equally use the second code block to achieve the same thing?