Counter (typography)

Storey refers to the number of open or closed stacked counters, especially in the context of the letters a and g and their typographic variants.

Fonts designed for legibility often have very open apertures, keeping the strokes widely separated from one another to reduce ambiguity.

Shapes like ‘C’ and ‘S’ curl back into themselves, leaving tight "apertures"—the channels of white between a letter’s interior and exterior...

Grotesque or neo-grotesque sans-serif fonts like Helvetica use very closed apertures, folding up stroke ends to make them closer together.

Closed letterforms on highly condensed grotesque designs such as Impact and Haettenschweiler make characters such as 8 and 9 almost indistinguishable at small print sizes.