The choice of font format is mostly based on the kind of documents you create and your computer environment. Here are some general guidelines.
OpenType® is a font format developed by Microsoft and Adobe. There are two "flavors" of OpenType:
- TrueType®-based outlines (.TTF)
- PostScript®-based outlines (.OTF)
TrueType fonts have .TTF file extension. TrueType is the default font format of both Macintosh and Windows systems. TrueType fonts are popular among home users & office users, enterprises and software & hardware developers. If this is the first time you are buying a font, then pick TrueType and you won't go wrong. Note: TrueType fonts from Ascender have the same icon as OpenType fonts.
The term 'OpenType' is often used by graphic designers and creative professionals to refer to OpenType fonts containing PostScript® outlines. These OpenType fonts have a .OTF file extension. OpenType fonts have replaced the original "PostScript Type 1" fonts as creative professionals upgrade their systems.
Both TrueType and OpenType fonts are easy to install, and the same file can be use on either Mac OS X or Windows. The main difference in the fonts can be found "under the hood": each font format uses a different technique in drawing and rendering the character outlines.
To use an OpenType font that contains advanced typographic features you must have an OpenType-savvy application. Examples include Adobe Creative Suite, QuarkXPress, Melell, iWork, and Word 2010 & Publisher 2010. Each application varies in the OpenType features they support, and how you access the features.
OpenType fonts can have some amazing features in them to create high quality typographic effects. The features may include oldstyle figures, true small capitals, fractions, superiors, inferiors, ligatures, swashes, titling letters, contextual alternates and stylistic alternates. Note: every OpenType font is different, and may not have all these features.