Design and Architecture

<InsertItemTemplate>
  <asp:DropDownList id="ddlStatusInsert" runat="server" >
    <asp:ListItem Value="">Unknown</asp:ListItem>
    <asp:ListItem>Available</asp:ListItem>
    <asp:ListItem>Out of Service</asp:ListItem>
    <asp:ListItem>Closed</asp:ListItem>
    <asp:ListItem>Lost</asp:ListItem>
  </asp:DropDownList> 
</InsertItemTemplate>

1   abstract class Brush<br />
2     {<br />
3         protected Color c;<br />
4         public abstract void Paint();<br />
5 <br />
6         public void SetColor(Color c)<br />
7         { this.c = c; }<br />
8     }<br />
<br />
1   class BigBrush : Brush<br />
2     {<br />
3         public override void Paint()<br />
4         { Console.WriteLine("Using big brush and color {0} painting", c.color); }<br />
5     }<br />
1   class SmallBrush : Brush<br />
2     {<br />
3         public override void Paint()<br />
4         { Console.WriteLine("Using small brush and color {0} painting", c.color); }<br />
5     }<br />
1   class Color<br />
2     {<br />
3         public string color;<br />
4     }<br />
1 class Red : Color<br />
2     {<br />
3         public Red()<br />
4         { this.color = "red"; }<br />
5     }<br />
1    class Green : Color<br />
2     {<br />
3         public Green()<br />
4         { this.color = "green"; }<br />
5     }<br />
1   class Blue : Color<br />
2     {<br />
3         public Blue()<br />
4         { this.color = "blue"; }<br />
5     }<br />
 1     class Program<br />
 2     {<br />
 3    public static void Main()<br />
 4   {<br />
 5     Brush b = new BigBrush();<br />
 6     b.SetColor(new Red());<br />
 7     b.Paint();<br />
 8     b.SetColor(new Blue());<br />
 9     b.Paint();<br />
10     b.SetColor(new Green());<br />
11     b.Paint();<br />
12 <br />
13     b = new SmallBrush();<br />
14     b.SetColor(new Red());<br />
15     b.Paint();<br />
16     b.SetColor(new Blue());<br />
17     b.Paint();<br />
18     b.SetColor(new Green());<br />
19     b.Paint();<br />
20   }<br />
<br />
2.Gof defines the bridge pattern as Decouple an abstraction from its implementation so that the two can vary independently.<br />
<br />
question:<br />
According to item 1 ,how to comprehend the definition of Bridge pattern by Gof ?Especially, what does the "abstraction" and "implementation " Gof stand for?

Class classA()
{

}

Class classB{

      public MethodA(classA obj)
       {
       }
}