What Is Font ?

A computer font (or fount) is an electronic data file containing a set of glyphs, characters, or symbols such as dingbats. Although the term font once referred to interchangeable typefaces using mechanical components such as a typeball element or a daisy wheel, most modern fonts are used in computing. There are three basic kinds of computer font file data formats:

* Bitmap fonts consist of a series of dots or pixels representing the image of each glyph in each face and size.
* Outline fonts use Bézier curves, drawing instructions and mathematical formulas 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 and size, which together describe the appearance of the glyph.

Bitmap fonts are faster and easier to use in computer code, but inflexible, requiring a separate font for each size and each face. Outline and stroke fonts can be resized using a single font and substituting different measurements for components of each glyph, but are somewhat more complicated to use than bitmap fonts as they require additional computer code to render them. For example, the letter "A" has three components, the two lines on the outside and the bar between the two outside lines, and may have more if the design has serifs.

Bitmap fonts versus outline fonts can be compared to the two main types of image file formats. Bitmap image formats such as Windows Bitmap (.bmp), Portable Network Graphics (.png) and Tagged Image Format (.tif or .tiff), store the image data as a grid of pixels, in some cases with compression. Outline or stroke image formats such as Windows Metafile format (.wmf) and Scalable Vector Graphics format (.svg), store instructions of how to draw the image rather than storing the image itself.

A bitmap image can be displayed in a different size only with some distortion, but renders quickly; outline or stroke image formats are resizable but take more time to render as pixels must be drawn from scratch each time they are displayed.

Fonts are designed and created using font editors. Fonts specifically designed for the computer screen and not printing are known as screenfonts.

Font formats

Type 1 and Type 3 Fonts

Type 1 and Type 3 fonts were developed by Adobe for professional digital typesetting. Using PostScript, the glyphs are outline fonts described with cubic Bezier curves. Type 1 fonts were restricted to a subset of the PostScript language, and used Adobe's hinting system, which used to be very expensive. Type 3 allowed unrestricted use of the PostScript language, but didn't include any hint information, which could lead to visible rendering artifacts on low-resolution devices (such as computer screens and dot-matrix printers).

TrueType Font

TrueType is a font system originally developed by Apple Computer. It was intended to replace Type 1 fonts, which many felt were too expensive. Unlike Type 1 fonts, TrueType glyphs are described with quadratic Bezier curves. It is currently very popular and implementations exist for all major operating systems.

OpenType Font

OpenType is a smartfont system designed by Adobe and Microsoft. OpenType fonts contain outlines in either the TrueType or Type 1 (actually CFF) format together with a wide range of metadata.

METAFONT

METAFONT uses a different sort of glyph description. Like TrueType, it is a vector font description system. It draws glyphs using strokes produced by moving a polygonal or elliptical pen approximated by a polygon along a path made from cubic Bézier splines and straight line segments, or by filling such paths. Although when stroking a path the envelope of the stroke is never actually generated, the method causes no loss of accuracy or resolution.