What does achieving a correlation coefficient of +1.0 confirm about two variables?

Answer

They track each other almost perfectly.

A perfect correlation ($r = 1.0$ or $r = -1.0$) only establishes that the variables move together linearly; it never proves that one causes the other.

What does achieving a correlation coefficient of +1.0 confirm about two variables?
relationshipmethodstatisticcorrelationcausation