The Microsoft® Win32® application programming interface (API) provides three types of combo box: simple combo boxes (CBS_SIMPLE), drop-down combo boxes (CBS_DROPDOWN), and drop-down list boxes (CBS_DROPDOWNLIST).
There are also a number of combo box styles that define specific properties. For example, two styles enable an application to create an owner-drawn combo box, making the application responsible for displaying information in the control.
A combo box consists of a list and a selection field. The list presents the options a user can select and the selection field displays the current selection. Except in drop-down list boxes, the selection field is an edit control and can be used to enter text not in the list.