The work area (user interface) > Selection tools > Selection cursors
  
Selection cursors
By observing the cursor when you make selections, you can easily see the context of your selection. For example, the cursor indicates that a multiple selection has been started with at least one item selected and with right-click command-specific options. The selection cursors are explained below.
Single selection.
Single selection with right-click command-specific options.
Multiple selection possible.
Multiple selection started with at least one item selected. Press the middle mouse button to complete the selection list.
Multiple selection possible with right-click command-specific options.
Multiple selection started with at least one item selected and with right-click command-specific options. Press the middle mouse button to complete the selection list.
Delete 2D.
Delete 3D.
Add to drawlist.
Remove from drawlist.
Select a reference face in the viewport for selection of faces using geometry rules.