The Gaia Ajax HiddenField depresents a hidden field used to store a non-displayed value. It inherits from the ASP.NET Button, and has built-in Ajax behaviour.
1:
2: <gaia:Button runat="server" ID="zButton" Text="Get value of HiddenField"
3: OnClick="zButton_Click" />
4: <gaia:Label ID="zLabel" runat="server" />
5: <gaia:HiddenField runat="server" ID="zHiddenField" Value="I am hidden, so you can't see me" />
6: