They are not complicated. They are common - that's the whole thing behind them. They are so common that it's useful to use same names to talk about them because

They are not complicated. They are common - that's the whole thing behind them. They are so common that it's useful to use same names to talk about them because you will see them over and over in the code of different persons. And certainly defining them exactly and having good implementation examples might also occasionally help a programmer as we're not all perfect ;-)