There might be things that you have seen your whole life but never considered the purpose of. Take the p-trap for example. Every sink, shower or toilet that you ever have used has one, but do you know what it is for?
The simple answer is that it works as a seal between the sewer and your living area. This is needed because inside of the drainage pipes that you have in your home, there is a harmful, foul-smelling gas called sewer gas. The reason why a p-trap has that signature bend on it is because the water functions as a valve of sorts. It will allow water and other items to pass through, while the gas can’t travel back up.
So, the next time you look under your sink and you see that strangely shaped pipe, be thankful that it keeps you from being overwhelmed by sewer gas every day.