In the past, a typical Western PostScript font was limited to 256 glyphs, forcing you to install and manage two or more style-related fonts in order to access "expert set" characters. OpenType significantly simplifies font management and the publishing workflow by ensuring that all of the required glyphs for a document are contained in one cross-platform font file throughout the workflow. OpenType fonts may contain more than 65,000 glyphs, which allows a single font file to contain many nonstandard glyphs, such as old-style figures, true small capitals, fractions, swashes, superiors, inferiors, titling letters, contextual and stylistic alternates, and a full range of ligatures.
Historically, some of the highest quality typefaces have included different designs for different print sizes. Several of Adobe's OpenType fonts include four optical size variations: caption, regular, subhead and display. Called "Opticals," these variations have been optimized for use at specific point sizes. Although the exact intended sizes vary by family, the general size ranges include: caption (6-8 point), regular (9-13 point), subhead (14-24 point) and display (25-72 point).