Diacritic
This is an accented character, which you mostly see in languages other than U.S. English. French, for example, uses several diacritics, like in “façade” and “café”. Vietnamese uses accented characters in almost every word.
Why I Looked It Up
I was using a software tool to search filename on my computer, and one of the options was “Use Diacritics” (or not).
Also, I remember writing some code once that replaced diacritics with their “normal” ASCII counterpart – like “facade” and “cafe.”