A computer font is implemented as a digital data file containing a set of graphically related glyphs, characters, or symbols such as dingbats. A font family or typeface refers to the collection of related fonts across styles and sizes, there are three basic kinds of computer font file data formats, Bitmap fonts consist of a matrix of dots or pixels representing the image of each glyph in each face and size. Outline fonts use Bézier curves, drawing instructions and mathematical formulae to describe each glyph, which make the character outlines scalable to any size. Stroke fonts use a series of specified lines and additional information to define the profile, or size and shape of the line in a specific face, Bitmap fonts are faster and easier to use in computer code, but non-scalable, requiring a separate font for each size. Although all types are still in use, most fonts seen, fonts are designed and created using font editors. Fonts specifically designed for the screen and not printing are known as screen fonts. Fonts can be monospaced or proportional, however, the particular font-handling application can affect the spacing, particularly when doing justification. A bitmap font is one that each glyph as an array of pixels. It is less known as a raster font. Bitmap fonts are simply collections of images of glyphs. For each variant of the font, there is a set of glyph images. For example, if a font has three sizes, and any combination of bold and italic, then there must be 12 complete sets of images, advantages of bitmap fonts include, Extremely fast and simple to render Easier to create than other kinds. The limited processing power and memory of computer systems forced exclusive use of bitmap fonts. Bitmap fonts are used in the Linux console, the Windows recovery console, older dot matrix printers used bitmap fonts, often stored in the memory of the printer and addressed by the computers print driver. Bitmap fonts may be used in cross-stitch, to draw a string using a bitmap font, means to successively output bitmaps of each character that the string comprises, performing per-character indentation. Digital bitmap fonts may use monochrome or shades of gray, when displaying a text, typically an operating system properly represents the shades of gray as intermediate colors between the color of the font and that of the background. However, if the text is represented as an image with transparent background, Bitmap fonts look best at their native pixel size. Some systems using bitmap fonts can create some font variants algorithmically, for example, the original Apple Macintosh computer could produce bold by widening vertical strokes and oblique by shearing the image
Comparison between printed (top) and digital (bottom) versions of Perpetua.
With stroke-based fonts, the same stroke paths can be filled with different stroke profiles resulting in different visual shapes without the need to specify the vertex positions of each outline, as is the case with outline fonts.