SketchUp, by default, uses the lower left corner of the selection bounding box to set the component’s axis origin. This default point may not be the best in all cases. The axes origin is shown in SketchUp as red, green, and blue lines intersecting at their “origin.” The axes origin serves two purposes in SketchUp:

The red, blue, and green axes seen when you first open a new SketchUp model are not only starting points but guides you can use throughout the modeling process. Adjusting the SketchUp drawing axes makes drawing a 3D model easier. Here's some examples: