TTF(TrueTypeFont) is a font file format jointly launched by Apple and Microsoft. With the popularity of windows, it has become the most commonly used font file representation. In some special occasions, the system character set does not contain the font you want to use. At this time, you must use your own font files, such as ancient Chinese characters such as Oracle Bone Inscriptions. Generally, you can double-click the system disk \WINDOWS\Fonts to see what kind of font it is.