OpenType is a modern font-file format whose benefits include cross-platform support, simple file management, advanced typography, expanded glyph sets, and compatibility through open standards.
Microsoft and Adobe released the OpenType (OTF) specification in the 1990s as a superset of TrueType (TTF) and Adobe’s PostScript Type 1 formats. By 2005, Adobe and Microsoft had made it an open standard and foundries were offering their fonts in the new OTF format.
Portability and Compatibility
OpenType fonts not only work on both Mac and Windows, but they also use the same character encoding on both operating systems. Therefore, when you open the same document on either platform, there’s no character substitutions that require search-and-replace correction. In addition, OpenType fonts can be combined in documents with TrueType and Postscript fonts, and are compatible with modern printers and imaging devices.
One Cross-Platform File
An OpenType font contains all outline, bitmap and font metric data in a single file that can include glyph variations of all kinds. This centralization simplifies the administration of font collections and the use of font management software.
Expanded Glyphs and Typesetting
OpenType fonts can contain 65,535 glyphs, enabling virtually limitless support for accented characters, ligature sets, alternate characters, small caps, symbols, fractions, dingbats, currencies, drawing characters and international language support. This can eliminate the need for multiple versions of the same typeface.
Extensive Language Support
OpenType’s support for virtually any number of glyphs enables designers to support character sets for multiple languages in a single font. It is common to see OpenType fonts include accented, Greek and Cyrillic characters in their glyph sets. In addition, since it supports Unicode, OpenType includes multi-byte character encoding that supports all of the world’s languages.
Ligature and Glyph Substitution
Modern applications that are OpenType-compatible can automatically detect adjacent characters for which a font has a defined ligature. The same feature can automatically add special design characters such as brush strokes or swashes to the beginning or end of character strings.
Choice of Font Outlines
OpenType allows font designers to include their choice of outline data, either TrueType Format (TTF) or Compact Font Format (CFF) used by PostScript fonts. While TrueType outlines require more anchor points and are therefore larger, they are faster to process and sharper on low-res displays — but it all happens automatically, so you might not notice. Just know that you can depend on OpenType fonts with TTF or CFF outlines to work predictably in your documents.
Future-Proofing Via Open Standards
Even though font standards move slowly and support for old formats continues for years, it’s important to note that OpenType is based on open industry standards. This makes it by far the safest, longest-lived and most cost-effective format on which to build your font collection.
Choose OpenType When You Can
All these details boil down to a simple recommendation to choose OpenType fonts when you can. This applies when you are purchasing or downloading fonts, as well as when you have the choice of selecting a TrueType, Type 1 or OpenType version of a font in a document or design. When you do, you will be getting the latest and greatest version of the font for your creations.