Modern computer fonts are called outline fonts because of the way they are stored. Rather than being actual bitmap images of the characters, an outline font consists of a set of rules about how each character is to be rendered, enabling the font to be displayed at essentially any size with no loss in quality—in other words, the fonts are scalable. It also permits special effects such as rotation to be performed. TrueType fonts were the first scalable fonts for Windows, and more recently the OpenType font specification was introduced. When you use the Font applet (available in the Control Panel) to view your installed fonts, TrueType fonts are represented with a TT icon and OpenType fonts by an O icon, as shown in Figure 2. Older bitmapped fonts, which are not supported by .NET, are represented by an A icon.
Figure 2 The Font applet displays installed fonts with an icon identifying their type.
At the highest level, fonts are organized into font families. The fonts in a given family differ in the details, but are the same in overall appearance. Some of the more popular font families are Courier, Times, Arial, and Helvetica. The fonts within a family can vary by being wider or narrower, by being heavier or lighter, or by being slanted. Most fonts are variable pitch fonts, sometimes called proportional spaced fonts, which means that the amount of horizontal space a character takes up depends on its width—an m takes up more space than an i, for example. In fixed pitch fonts, such as Courier, all characters take up the same amount of horizontal space.
Font size is traditionally specified in points. A point is an old printer’s measurement that is equal to 1/72 of an inch. You can think of a font’s size as the distance from the top of the tallest letter to the bottom of the lowest letter. Because of variability between fonts, it is not a precise measurement (12 point Times is not precisely the same size as 12 point Arial), but it is close.