Which scalable font technology did Windows 3.1 introduce?

Windows 3.1 introduced the TrueType scalable font technology. Instead of storing letters as fixed-size bitmap images, TrueType described each glyph with mathematical outlines that could be rendered at different sizes and resolutions.

Microsoft developed TrueType with Apple, and Windows 3.1 used it to provide high-quality fonts without requiring Adobe Type Manager, Adobe’s competing font system. The release included familiar typefaces such as Arial, Courier New, and Times New Roman, each available in regular, bold, italic, and bold-italic styles. TrueType fonts could also be scaled and, where software supported it, rotated.

A common mix-up is OpenType, which arrived later as a more advanced font format developed by Microsoft and Adobe. ClearType is different again: it is a later Microsoft display-rendering technology designed to improve the appearance of text on LCD screens. PostScript is a page-description and font technology associated especially with Adobe, not the technology Windows 3.1 introduced as its built-in scalable-font system.