AllowUserToOrderColumns property of the DataGridView give user flexibility to arrange the column order in what they want to view data.
If you want that user can re arrange the column at set this AllowUserToOrderColumns of the DataGridView to true.
Similarly if you want user to restrict not to change the column order set this property to false.
Code sample in C#
myDataGridView.AllowUserToOrderColumns = true; //myDataGridView is my DataGridViewName
Note: by default its true only.