Digital type became the dominant form of type in the late 1980s and early 1990s. Digital fonts store the image of each character either as a bitmap in a bitmap font, or by mathematical description of lines and curves in an outline font, also called a vector font. Bitmap fonts were more commonly used in the earlier stages of digital type, and are rarely used today.
When an outline font is used, a rasterizing routine (in the application software, operating system or printer) renders the character outlines, interpreting the vector instructions to decide which pixels should be black and which ones white. Rasterization is straightforward at high resolutions such as those used by laser printers and in high-end publishing systems. For computer screens, where each individual pixel can mean the difference between legible and illegible characters, some digital fonts use hinting algorithms to make readable bitmaps at small sizes.