Plumbing in a nutshell - Wikipedia
Wikipedia tells us a little about what plumbing really is:
Plumbing is the system of pipes, drains, fittings, valves, and fixtures installed for the distribution of potable water for drinking, heating and washing, and waterborne waste removal. "Plumbing" also refers to a skilled trade which deals with installation and maintenance.
The plumbing industry is a basic and substantial part of every developed economy. The word derives from the Latin plumbum for lead, as the first effective pipes used in Roman era were lead pipes.
"Plumbing" often denotes the supply and waste system of an individual building, distinguishing it from water supply and sewage systems that serve a group of buildings.
Plumbing - pipe types
Constructing your plumbing and drainage installation, isn't as straightforward as it may seem. First thing you need to choose, is what type of pipes are you going to use? There is plenty to choose from, but not all are multi purpose and good for your home.
Generally speaking, you need the ones relatively easy to install, repair if needed and with long life span. Price is also relevant, of course, but sometimes it is better to pay up more up front, rather than upgrade it later.
The answer to such problem is only one - PEX pipes. You might thought that copper pipes are better, but they aren't - harder to install and much more expensive. All in all, pipes from PEX are very good, either for the plumber or user. The only thing that's left, is to find were you can get them cheapest, and in required diameters.
Plumbers and their heritage by Wikipedia
Wikipedia provides us with brief history of the plumbers:
The word "plumber" dates from the Roman Empire. The Latin for lead is plumbum. Roman roofs used lead in conduits and drain pipes and some were also covered with lead, lead was also used for piping and for making baths. In medieval times anyone who worked with lead was referred to as a plumber as can be seen from an extract of workmen fixing a roof in Westminster Palace and were referred to as plumbers "To Gilbert de Westminster, plumber, working about the roof of the pantry of the little hall, covering it with lead, and about various defects in the roof of the little hall". Thus a person with expertise in working with lead was first known as a Plumbarius which was later shortened to plumber.