[kindall]

Hinting is what that's called.

[raphlinus]

I think ~warent is referring to features like ink traps, which are features that do look strange up-close, but might help increase contrast or other qualities at small sizes.

[nyanpasu64]

Maybe overshoot as well?

[FoundersGrotesk]

Hinting is the explicit adjustment of a font’s outlines to snap it to the pixel grid. It’s a similar outcome, but different process.

[mmmrk]

That's a separate concept, he probably means ink traps and optical size adjustments.