A font is essentially the design for a set of characters. It's the combination of typeface and design characteristics such as size, pitch and spacing. The height of characters in a font is measured in points, each point being approximately 1/72 inch. The width is measured by pitch, which refers to how many characters can fit in an inch. Common pitch values are 10 and 12. A font is said to be fixed pitch if every character has the same width (this type of font is also called monospace). If the widths vary depending on the shape of the character, it is called a proportional font.
A font family is a group of fonts that have similarities in design. One member of the font family may be bold, while another member of the same family may be italic (these characteristics are also referred to as font style). Families are generally grouped into categories based on design specifications such as serifs, fonts that resemble handwriting, or even its proportional spacing. The five generic font families consist of fonts in the categories of serif, sans-serif, cursive, fantasy and monospace. There are other font families such as Times, Script, Arial and Courier to name but a few of the more popular families.
Typeface vs. Font
The term font is often used as a synonym for typeface, which is not technically correct. For example, some may refer to Times Roman as a font, but it is actually a typeface that defines the shape of each character. Within the Times Roman typeface there are many fonts to choose from — different sizes and styles (e.g., italic, bold and so on).
Today many people use the word font to generally refer to the computer files saved (or stored) on our computers, which is why the synonymous use of the two terms exists today. If you have the Times New Roman typeface installed on your computer, then you can make it most any size — from tiny to huge, italic or bold. Where the terms font and typeface, by definition, mean two different things, the capability to manipulate a typeface so easily on the computer means the two terms are often used as interchangeable terms now. When referring to printing and document creation on a computer at home or in the office this typically isn't an issue
When working with a printer or service bureau, however, the difference between the two terms become relevant. In that scenario, you cannot simply make Times Roman bold by selecting bold in the Style menu of your graphics or publishing application. To properly output your file to a high-resultion device such as an imagesetter, you need to provide your vendor a Times Roman Bold printer font. It is in this area of the printing industry where the term typeface and font do mean two different things and the word font is not able to be used as a synonym for typeface.
Bit-Mapped & Vector Graphics System Fonts
Computers and devices use two methods to represent fonts. One is a bit-mapped font where every character is represented by an arrangement of dots. To print a bit-mapped character, a printer simply locates the character's bit-mapped representation stored in memory and prints the corresponding dots. Each different font, even when the typeface is the same, requires a different set of bit-maps.
The second method uses a vector graphics system to define fonts. In vector graphics systems, the shape or outline of each character is defined geometrically. The typeface can be displayed in any size, so a single font description really represents innumerable fonts. For this reason, vector fonts are called scalable fonts as they can be scaled to any size.
A scalable font is really one font in which the outlines of each character are geometrically defined. The most popular languages for defining scaleable fonts are PostScript and TrueType.
PostScript is an object-oriented language, meaning that it treats images, including fonts, as collections of geometrical objects rather than as bit maps. PostScript fonts are called outline fonts because the outline of each character is defined. They are also called scalable fonts because their size can be changed with PostScript commands. Given a single typeface definition, a PostScript printer can thus produce a multitude of fonts. In contrast, many non-PostScript printers represent fonts with bit maps. To print a bit-mapped typeface with different sizes, these printers require a complete set of bit maps for each size.
An outline font is scalable because, given a geometrical description of a typeface, a printer or other display device can generate the characters at any size. What differentiates a scalable font from an outline font (aside from offering innumerable sizes of each font) is that outline fonts have the added advantage that they make the most of an output device's resolution. The more resolution a printer or monitor offers, the better an outline font will look.
Aside from the scalability of vector fonts, their other main advantage over bit-mapped fonts is that they make the most of high-resolution devices. Bit-mapped fonts look almost the same whether printed on a 300-dpi printer or a 1,200-dpi printer. In contrast, vector fonts look better at a higher the resolution.
Despite the advantages of vector fonts, bit-mapped fonts are still widely used. One reason for this is that small vector fonts do not look very good on low-resolution devices, such as display monitors (which are low-resolution when compared with laser printers). Many computer systems, therefore, use bit-mapped fonts for screen displays. These are sometimes called screen fonts. A screen font basically resembles the font for a document, so that what you see on the screen will look very similar to the end-result (printed document).
With vector fonts seem to offer more benefits, some professionals still prefer to use bit-mapped fonts on high-resolution printers because characters can be individually tailored to the printing device. An additional drawback of vector fonts is that every character must be generated as it is needed. This is a computation-intensive process that requires a powerful microprocessor to make it acceptably fast.
Based in Nova Scotia, Vangie Beal is has been writing about technology for more than a decade. She is a frequent contributor to EcommerceGuide and managing editor at Webopedia. You can tweet her online @AuroraGG.