The .ttf file extension represents a TrueType Font file. TrueType is a font standard developed by Apple and Microsoft in the late 1980s as a competitor to Adobe's Type 1 fonts. It became one of the most common formats for fonts used in both macOS and Windows operating systems. TrueType fonts are scalable, meaning they can be resized without losing quality, making them suitable for both screen display and printing. The format contains glyph data, which defines the shapes of characters, as well as hinting information, which helps to improve the appearance of the font at small sizes. TrueType fonts are widely supported by various applications, including word processors, graphic design software, and web browsers. They are essential for displaying text correctly and consistently across different devices and platforms. The format's open specification has contributed to its widespread adoption and longevity.