A private residence is a good example of a private zone. Division between zones is generally accomplished with some type of barrier. These can be either physical or symbolic. Physical barriers, as the name implies, are substantial in nature and physically prevent movement. Fencing, some forms of landscaping, locked doors, and the like are examples of physical barriers.
Symbolic barriers are less tangible.
Nearly anything could serve as a symbolic barrier. The only requirement is that it define the boundary between zones. This type of barrier does not prevent physical movement. All that is required is that it leave no doubt that a transition between zones has taken place. Low decorative fences, flower beds, changes in sidewalk patterns or materials, and signs are examples of symbolic barriers.