Western figures – also known as digits or numerals – come in two main styles: lining and old style. Lining figures are the most common today and are the default in most typefaces. Lining figures are of uniform height, reaching from the baseline to the cap-height of the font. Old-style figures are in a sort of "lower case" style, and, fittingly, are meant to be shown alongside lowercase text. Old-style figures have different heights, with some reaching below the baseline. They are typically a bit smaller than lining figures.

Many OpenType fonts include support for both styles of figures.

Lining figures	Old-style figures

Old-style figures do not stand out as much within a page of text and are more refined. Compare how the same paragraph looks with lining and old-style figures.

Lining figures example.

Old-style figures example.

Sample text from "Where does the term '86' come from?," from The Straight Dope.