Counter may refer to:

Mathematics and computing

Games and sport

See also

In typography, a counter is the area of a letter that is entirely or partially enclosed by a letter form or a symbol (the counter-space/the hole of). Letters containing closed counters include A, B, D, O, P, Q, R, a, b, d, e, g, o, p, and q. Letters containing open counters include c, f, h, i, s etc. The digits 0, 4, 6, 8, and 9 also possess a counter. An aperture is the opening between an open counter and the outside of the letter.

The lowercase 'g' has two typographic variants: the single-story '' has one closed counter and one open counter (and hence one aperture); the double-story '' has two closed counters.

Open and closed apertures

Different typeface styles have different tendencies to use open or more closed apertures. This design decision is particularly important for sans-serif typefaces, which can have very wide strokes making the apertures very narrow indeed.

Fonts designed for legibility often have very open apertures, keeping the strokes widely separated from one another to reduce ambiguity. This may be especially important in situations such as signs to be viewed at a distance, materials intended to be viewed by people with vision problems, or small print, especially on poor-quality paper. Fonts with open apertures include Lucida Grande, Trebuchet MS, Corbel and Droid Sans, all designed for use on low-resolution displays, and Frutiger, FF Meta and others designed for print use. This design trend has become increasingly common with the spread of humanist sans-serif designs since the 1980s and the 1990s and the use of computers requiring new fonts which are legible on-screen.