Wikipedia on - casually about plumbing
Plumbing (which comes from the Latin word plumbum, which means lead, as pipes were once made from lead) is the job of working with pipes, tubing and plumbing fixtures for drinking water systems and getting rid of waste. A plumber is someone who fixes or puts in piping systems, plumbing fixtures and equipment such as water heaters. Many plumbers are construction workers. The plumbing industry is an important part of every developed economy because people need clean water and safe ways to move and store waste.
Plumbing also refers to a system of pipes and fixtures put in a building to move water and the get rid of waste that is in water. Plumbing is different from water and sewage systems because plumbing system serves one building, while water and sewage systems serve a group of buildings or a city.
Źródło: https://simple.wikipedia.org/wiki/Plumbing
Wikipedia about the history of the plumbers
Quick look in to the history of the plumbers, thanks to Wikipedia:
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.
Źródło: https://en.wikipedia.org/wiki/Plumber
Calling Plumber or doing it yourself?
When it comes to repairing things around the house, men often feel compelled to do it themselves, rather than spent money on overpriced expert. More often than not, it is worth the effort, but what happens when you mess with crucial installations, that you know very little about?
Broken chair or squeaky hinges are one thing, but if you mess up with your drainage or plumbing, all hell can break loose. From time to time, it is really wise to call in the plumber - you may pay more than you would want to, but not necessary more than it is worth. Especially if you would do this yourself and mess up.
Besides, do you really have all the necessary things for all the repairs? I doubt that, let alone the tools, which you may or may not have. If you buy unnecessary spare part, what will you do with it? Plumber can always use it, but he probably wouldn't make the mistake in the first place.
To sum up, it is good to do things around your house by yourself, but don't be afraid to call in the specialist from time to time.