AssociatedControlID Property of Label Control

In ASP.Net Label control, there is a property called AssociatedControlID. This property changes the behaviour of the label control after rendering.

e.g. We have a label control...

<asp:Label ID="lblSearch" Text="Search" runat="server" />

After running the page, go to so View --> Source... and you will get like this :

<span id="lblSearch">Search</span>

This means label contol render to a simple html element.

So, after adding the AssociatedControlID property and taking a contol (I'm taking a text box) to be associated...

<asp:Label ID="lblSearch" Text="Search" runat="server" associatedcontrolid="txtSearch"/>
<asp:textbox id="txtSearch" runat="server"/>

Now run the page and go to View --> Source...You will find something different.

<label id="lblSearch" for="txtSearch">Search</label>
<input id="txtSearch" name="txtSearch">

Now the Label control rendered a html element with the 'for' property set.

This links the label to another server control. When you click on the label control, you can get the focus in the associated control.(You will get the focus in the textbox 'txtSeach' in the above sample.)

This is also good for accessibility, allows hotkeys to be set for the associated control to set the focus.
Syntax is as follows:

<asp:label id="lblSearch" accesskey="S" runat="server" text="Search" associatedcontrolid="txtSearch"><asp:textbox id="txtSearch" runat="server">

Here the AccessKey property set the hotkey.
When you'll press Alt+S (or Ctrl+Alt+S in Firefox), the textbox will be focused.