Allowing the selection of zero or more items from a list whose items are not mutually exclusive. "Check all that apply" comes to mind as a good heading. As with radio buttons, check boxes can be initially selected.
When the control type of a variable or an attribute is a Check Box, besides the properties described in the Attribute/Variable Control properties, in web forms you can assign a value to these properties:
A Check Box is a two state control that indicates whether a certain condition or value is on or off, true or false. The display state of a check box is always either "checked" or "unchecked".
Note: "unchecked" value is assigned by default.
Attribute/Variable Control Properties in Web Forms