The term describes the rights associated with a physical structure or improvement permanently affixed to land. It encompasses the legal concept that once personal property is attached to real property in such a way that it becomes an integral part of it, it transforms into real property. An example is the installation of a central air conditioning unit in a house; the unit, once installed, is typically considered part of the real estate and transfers with the property upon sale.
Understanding the concept is crucial in property law, real estate transactions, and taxation. It clarifies ownership boundaries and determines what is included in a sale or lease. Historically, the concept arose to prevent disputes over removable fixtures and to ensure the value of land remains consistent and predictable. Proper identification of attached items avoids future conflicts and facilitates fair valuation of properties.