Groups are unintelligent containers that simply hold geometry. Groups can hold any collection of entities; edges, surfaces, images, text, components, and even other groups. If you make a copy of a group, there will be no connection between the original and the new copy. Groups are mainly used to contain entities to control the stickiness of geometry, and most importantly form a hierarchy of model organization.
Edges and surfaces stick together in SketchUp, often referred to as "stickiness of geometry". This can be frustrating at first, but once you learn to control the stickiness of geometry you will find that it drastically speeds up the modeling process. Stickiness can be controlled by placing geometry into a group.
A group captures the selection in an invisible shell. Follow these steps to make a group.
Once a group is created, you can no longer select the individual edges and surfaces. When you select the group, you will see a blue bounding box
HEADS UP! When in doubt... Group! It is almost impossible to make too many groups. It is far easier to explode, or "ungroup", than it is to pick through a blob of geometry to create new meaningful groups.
HEADS UP! I use the keyboard shortcut "G"
Inevitably you will need to access the contents inside of a group. The right-click method for editing groups is slow and methodical. Use this method when you're initially learning to navigate groups; it is easy to understand which container level of the model you are in. Follow these steps:
After you get comfortable with your location in the model, use the Select tool to navigate groups much faster. Follow these steps...
HEADS UP! When in group edit mode, and the Select tool is active, tapping the Escape key will also back you out one level.
Exploding a group removes the top-level invisible shell, exposing the contents. Keep in mind that the contents can be any entity; edges, surfaces, groups, components, images, text, etc., and even other groups. You can ungroup entities by using the Explode command.
HEADS UP! I use the keyboard shortcut "X"