Weak acids/bases tend to not fully convert their potential free ions, stabilizing at particular pHs for relatively large ranges of concentration.

You can use that as a basis for solutions that aren't super-basic but will preserve their pH in response to drips of acid.

But please…go on.

Yep, we agree. I was just pointing out the overall pH doen not change, there are ways to avoid that. From the the previous comment it kimd of seemed as though if you put something acidic in, the overall acidity must increase, which is not the case, so I wanted to make sure random readers don't get the wrong idea.