With the file extension FON so-called generic font files, ie general font files are marked. The FON format was already used in Windows 3.X and has since been replaced by TrueType and OpenType fonts.
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.
Unlike TrueType fonts, FON fonts can not be scaled. In addition, it may happen that a printed document differs from the screen image. For these reasons, the FON format is no longer used. However, FON files can still be viewed and installed under Windows 7, but it is not recommended.
Most often resolving problems with opening FON files is very simple. Just install an appropriate program that supports such files. All of the listed programs support FON files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of FON 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 FON 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 FontForge applications is not on the list, select "Browse" option in order to manually locate the directory where FontForge has been installed.
Sometimes problems with opening FON files may not lie with the application itself, but can arise due to other causes, such as: