The System.Windows.Forms.ListView grouping feature lets you create visual groups of logically related System.Windows.Forms.ListView items. Each group consists of a text-based header followed by a horizontal line and the items assigned to that group. You can align the header text to the left, right, or center of the control. Any groups assigned to a System.Windows.Forms.ListView control appear whenever the ListView.View property is set to a value other than View.List.

System.Windows.Forms.ListView groups help your users find the items they are looking for by separating the items into useful categories. You can create whatever categories you need. One typical way to group the items is by the way they are sorted. For example, you can group the items by the initial letter of the item name when they are sorted alphabetically, or by subitems such as type or date when the list is sorted by clicking a column header in the details view. Windows Explorer uses this type of grouping.

To use the grouping feature, add one or more System.Windows.Forms.ListViewGroup objects to the ListView.Groups collection of a System.Windows.Forms.ListView control. Set the group header text and header alignment in the ListViewGroup.#ctor constructor, or set them using the ListViewGroup.Header and ListViewGroup.HeaderAlignment properties.

You can assign an item to a group by specifying the group in the ListViewItem.#ctor constructor, by setting the ListViewItem.Group property, or by directly adding the item to the ListViewGroup.Items collection of a group. All items should be assigned to groups before they are displayed. Any items that are not assigned to a group will appear in the default group, which has the header label "DefaultGroup{0}". The default group is not contained in the ListView.Groups collection, and cannot be altered. It is primarily useful in debugging to ensure that all items have been properly added to groups.

An item can only be in one group at a time. You can change the group to which an item belongs by setting the ListViewItem.Group property at run time or by adding it to the ListViewGroup.Items collection of another group, which automatically removes it from the previous group.