A specific width, weight, and style of a typeface.
Historically, a font referred to a complete set of metal type, and was also a specific size (such as 12-point). In e-publishing, computer fonts automatically generate varying sizes.
The term font is often used incorrectly to refer to a typeface, which is a collection of fonts intended to work together. For example, a typeface might include regular, bold, and italic fonts.
The issue is further confused because some desktop publishing programs automatically generate their own faux-bold and faux-italic effects. However, a professional-quality typeface includes separate fonts for each weight and stylistic variant.
Also see: typeface.