Attributes Eplaination is required

attributes are like properties of the Type or the member. and are not data in an instance.

suppose I have the following classes:

public class UserData1
{
   public string Text { get; set;}
   public string Name { get; set;}
   public string Address { get; set;}
}

public class UserData2
{
   public string Description { get; set;}
   public double Price { get; set;}
   public string StorageLocation { get; set;}
}

and suppose I have a reporting Utility, that wants to print out some of the properties.
I could go by implementing a ReportMe interface for each class, or an interface for each class, that only exposed the properties that I want.
with attributes, I can define

public class ReportableAttribute : Attribute {}

now you can mark classes and properties with this attribute:

[Reportable]
public class UserData1
{
   [Reportable]
   public string Text { get; set;}
   [Reportable]
   public string Name { get; set;}

   public string Address { get; set;}
}

[Reportable]
public class UserData2
{
   [Reportable]
   public string Description { get; set;}
   [Reportable]
   public double Price { get; set;}
   public string StorageLocation { get; set;}
}

now I can query an object, and all it's properties if they have this attribute

public void ReportObject(object target)
{
    bool report = false;
    //check if type is marked as Reportable
    foreach (Attribute a in target.GetCustomAttributes())
    {
    	if (a is ReportableAttribute)
    	{
    		report = true;
    		break;
    	}
    }
    if (report )
    {
    	PropertyInfo[] infos = target.GetType().GetProperties (BindingFlags.Public | BindingFlags.Instance | GetField);
           //check if property is marked as Reportable
            foreach (var propInf in infos)
            {
                foreach (Attribute b in propInf .GetCustomAttributes(false))
                {
                    if(b is ReportableAttribute)
                    {
                         this.Writer.Append(propInf.GetValue(target));
                         break;
                    }
                }   
            }
    }
}