Sitting, Lying, or Kneeling on the ground in an Outdoors environment, whether that be Grass, Dirt, Sand, Snow, Pavement, etc. A character on a Beach Towel or Blanket may be considered to be on the ground.
Don't use this tag for characters who are Standing upright, who are on a Simple Background (use Invisible Floor instead) or who are Indoors (use On Floor instead).