What defines a shared wall that contributes to two separate properties?

A shared wall that contributes to two separate properties is defined as a party wall. This type of wall is typically built on the boundary line between two properties and serves both property owners. It is common in situations such as townhouses or condominiums where homeowners may share walls for functional and aesthetic purposes.

The key characteristic of a party wall is that it is jointly owned and maintained by both parties and may have specific legal implications regarding repairs, modifications, or disputes that could arise between the neighboring property owners. This is distinct from other types of walls, such as fire walls, which are designed primarily for safety to prevent the spread of fire, retaining walls that support soil to prevent erosion, or boundary walls which demarcate the extent of property lines but do not serve a dual purpose for adjoining properties.