What is an Associated ControlID?

This is the property defined for a Label control in 2.0, which provides linking to an interactive control such as textbox,button,listbox and other asp.net controls. It defines a hot key which moves the input focus to the control defined in the property.

<asp:Label ID='Label1' runat='server' AssociatedControlID='TextBox1' Text='Enter Ur Details' 
 	Width='86px'></asp:Label>
<asp:TextBox ID='TextBox1' runat='server'></asp:TextBox>

In the above code, TextBox1 gets focused on clicking the Label1, sinced its AssociatedControlID is set to TextBox1.