The Hypertext Transfer Protocol (HTTP) is the dominant medium by which information is exchanged on the Internet. An Application Programming Interface (API) is a broad term that defines the rules that guide your interaction with some software. In the case of HTTP APIs, you have a defined set of endpoints that accept particular inputs. Plumber translates the annotations you place on your functions into an HTTP API that can be called from other machines on your network. If you execute your Plumber API on a public server, you can even make your API available to the public Internet.
Plumbing reached its early apex in ancient Rome, which saw the introduction of expansive systems of aqueducts, tile wastewater removal, and widespread use of lead pipes. With the Fall of Rome both water supply and sanitation stagnated—or regressed—for well over 1,000 years. Improvement was very slow, with little effective progress made until the growth of modern densely populated cities in the 1800s. During this period, public health authorities began pressing for better waste disposal systems to be installed, to prevent or control epidemics of disease. Earlier, the waste disposal system had merely consisted of collecting waste and dumping it on the ground or into a river. Eventually the development of separate, underground water and sewage systems eliminated open sewage ditches and cesspools.