A survey made to determine the actual physical extent of property ownership, typically witnessed by monuments or markers, such as (iron pipes, brass tags, or concrete monuments) which are drawn on a plat which is made part of the public record.
A Boundary Survey will always involve either a Record of Survey or a Corner Record, which is filed with the County Surveyor.
The State of California publishes a Plain Language Document that is useful is understanding the laws and issues relates to Land Surveys.
The use of high tech surveying equipment extends performance in the most challenging enviornment, like this hillside boundary survey.