In this article I have explain how to implement a Multiple Checkbox Select (MultiSelect) DropDownList with CheckBoxes.

The items will be dynamically added (inserted) and deleted (removed) from ListBox.

Grouping List Options The optgroup element is used to group options in a drop-down list, with the aim of making the list easier to navigate. The functionality essentially splits large numbers of items into small sections. Note that the label attribute is required, and will be rendered as the first item in the section. The user cannot select the label as a choice.