A more thorough explanation:

An outbuilding is a structure that is separate and detached from the main dwelling on a piece of land. It can be a barn, garage, shed, or any other type of building that is not connected to the main house.

Outbuildings can serve different purposes, such as storage, workspace, or housing for animals. They can also be used to define the boundaries of a property, known as curtilage. For example, a property owner may use the outermost outbuilding as the boundary for their yard.

One example of how outbuildings can be used to define curtilage is in California's Fish & Game Code § 3004. This law prohibits hunting or discharging a firearm within 150 feet of any outbuilding on someone else's property without their consent.

Another example is the Supreme Court case United States v. Williams, which discussed different ways to establish curtilage boundaries using outbuildings. The court suggested using the furthest outbuilding as the boundary or creating a "reasonable zone" beyond the outermost outbuilding.