delphi中未声明的标识符“ idhttp1”

我正在尝试从Delphi 2010中的URL加载图像。

我对Delphi很陌生，找到了这段代码，但是一直在获取：

idhttp1.get上未声明的标识符

我需要添加一些用途吗？谢谢

uses
  GIFImg;

procedure TForm1.btn1Click(Sender: TObject);
var
  MS : TMemoryStream;
  GIf: TGIFImage;
begin
  MS := TMemoryStream.Create;
  GIf := TGIFImage.Create;
  try
    IdHTTP1.get('http://www.google.com/intl/en_ALL/images/logo.gif',MS);
    Ms.Seek(0,soFromBeginning);       
    Gif.LoadFromStream(MS);
    img1.Picture.Assign(GIF);

  finally
    FreeAndNil(GIF);
    FreeAndNil(MS);
  end;
end;