My idea is to make the background color of my website yellow. But after making that change, how do I feel good about this actually having the intended consequence? Well, that's where significance tests come into play. What I would do is first set up some hypotheses, a null hypothesis and an alternative hypothesis. The null hypothesis tends to be a statement that, hey, your change actually had no effect. There's no news here. And so this would be that your mean is still equal to 20 minutes, is still equal to 20 minutes after, after the change to yellow, in this case, for our background.