The HTML CheckBox/RadioButton is selected only by clicking on the control and not the text associated with it. Using <Label>, you can bound the text with the CheckBox.
For instance, the following checkbox is selected only by clicking the checkbox:
<input type=checkbox name=c1>All Items
However, this checkbox can be selected either by clicking the checkbox or the text:
<input type=checkbox name=c1>
<Label for="c1">All Items</Label>
This works only in IE.