Just for those who don't know the difference

[Roscoe]

Oh yes, my favourite nerdish complaint. People who do not understand their own language. My personal trigger is the use of less instead of fewer. As in fewer aftershocks, not less...

Yes. It drives me nuts too. And while I'm mentally correcting the person I then miss out on listening properly to what they are actually saying.

The other one that has this effect on me is "between" (two people) versus "among" (three or more people).

That has now reminded me that recently I have seen confusion between "affect" and "effect".

Yes, you're correct, many people don't appear to know the difference between affect and effect, although it has been made simpler for the dummies among us now that the affect has been replaced (by the Americans and taken up by everyone else) by impact. Nothing has an affect any more. Everything now has an impact.