The file extension OTF features an OpenType font, a font standard for computers that was originally developed by Microsoft and later developed jointly with Adobe. Released in 1996, there were already a large number of OpenType fonts by the year 2000.
Fonts are in short all alphanumeric characters, special characters and partly international characters represented in a specific style and cut. Well-known fonts are for example Arial, Helvetica or Times New Roman.
An OTF file contains data in a tabular format, which includes either a TrueType or a Postscript Outline Font (in the so-called CFF format). OpenType fonts can have the endings orf and the file ends ttf, depending on their content. Often, the suffix ttf is used to maintain compatibility on systems that do not natively support OTF.
While font files that only contain Postscript fonts usually have the ending otf, font files with TrueType data can have both endings.
OTF fonts can be easily viewed and installed in Windows by double-clicking or using the shortcut menu, they are then automatically copied to the fonts folder and are immediately available. On the Mac (as of OSX) there are several fonts folders that can contain fonts. (eg System / Library, Library) To install, just copy the OTF file into one of the fonts folders or use the font collection.
Although OpenType is a registered trademark of Microsoft, the technology is available to all and may be used on any operating system. In addition to Windows, Mac OSX and Linux also support the OTF standard through the open source project Freetype. Since Font Rendering is an operating system function, all programs that fall back on it can automatically use OpenType fonts, but some programs can not access all special characters.
Most often resolving problems with opening OTF files is very simple. Just install an appropriate program that supports such files. All of the listed programs support OTF files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of OTF files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate OTF files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the Apple Font Book applications is not on the list, select "Browse" option in order to manually locate the directory where Apple Font Book has been installed.
Sometimes problems with opening OTF files may not lie with the application itself, but can arise due to other causes, such as: