In Navisworks, there is a concept of an active selection set (the currently selected items, or the current selection) and a saved selection sets. Selecting and finding items makes them part of the current selection, so you can hide them or override their colors. At any time, the current selection can be saved and named for retrieval in later sessions.
You can use several methods to interactively select items into the current selection. You can use the drop-down list in the Selection Tree, select items directly in the Scene View with the Select and Select Box tools, and you can select other items with similar properties to an existing selection using the selection commands.
You can also customize the level at which you select items using selection resolution, and modify the highlighting method for the items selected in the Scene View.