Many OpenType fonts have advanced features and alternate glyphs that lend to greater typographic usability. The way in which these features and glyphs are accessed depends upon the application that you are using.
Most professional design applications, such as those in Adobe Creative Suite, have OpenType menus that allow the user to activate the features relevant to the selected font.
Bickham Script Pro in InDesign CS3
Some applications do not yet have full support for OpenType fonts. While they will work on a basic level in almost any application on both Mac OS X and Windows, many of the features and alternate glyphs may not be accessible. Microsoft Office is the most notable of these. In a font like Bickham Script Pro, for example, you will not be able to access the swashes, ligatures, and contextual alternates that are included in the font.