TTF files are so called True Type Fonts files. 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. For example, if you change the font in Microsoft Word or another word processing program, you usually use one of the installed fonts.
Unlike bitmap fonts, True Type fonts are scalable through the use of descriptive vectors (outlines) and have the same display quality in every size. Developed by Apple, this technology was adopted by Microsoft for Windows and is now the standard on both systems. These TTF fonts are used not only for documents but also for displaying window contents or pictogram signatures. Often new fonts of programs (eg Word) are installed and are then also usable by other programs.
Anyone who wants to get an overview of the fonts installed in his system can simply go through the list of fonts in any word processing program. Under Windows you can also get a list with preview in the fonts folder under c: windows.
To install a TTF file downloaded from the Internet, for example, it is sufficient to select the item 'install' in the context menu (by right-clicking) the font file.
On the Mac (as of OSX) there are several fonts folders that can contain fonts. (eg System / Library, Library) To install, simply copy the TTF file into one of the fonts folders or use the font collection.
On Linux, it depends on the distribution. For most of the current ones, you can simply double-click TTF files and then choose Install Font.
In general, installed TTF font files can be used system-wide by any program. Thus, in addition to word processing programs and the graphics programs when using the text tool to it. To create new or edit existing TTF fonts there are several programs such as Fontforge or Fontlab Studio.
Most often resolving problems with opening TTF files is very simple. Just install an appropriate program that supports such files. All of the listed programs support TTF files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of TTF 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 TTF 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 TTF files may not lie with the application itself, but can arise due to other causes, such as: