Groups are SketchUp’s way of “sealing off” geometry, protecting one or more objects from affecting other objects and from being affected by other objects. A grouped set of objects also has the advantage of being selected as one object with one click, eliminating the need for dragging selection windows.
Many users are not clear on when to create a group and when to create a component. Geometrically, the two types of objects behave the same way: they are selectable as a single object, they are “sealed” from other objects, and they can be changed only when open for editing. As a general rule, these objects should be made into a group rather than a component:
Objects that need to be kept separate from other objects
Objects that will be used only once (will not be copied)
Objects that will eventually be exploded (such as objects used only for cutting or trimming)
Components are covered at length in Chapter 7, in which their advantages and many uses are discussed.
To create a group, you first select the objects to include in the group. You can then either choose Edit→Make Group from the main menu, or right-click on one of the selected objects and choose Make Group from the pop-up menu.
A group usually consists of more than one object. But you can still make a group from a single object. If only one face or edge is selected, Make Group will not appear in the pop-up menu, but you can still choose Edit→Make Group from the main menu. ...