Topic summary
Proportional font
Extracted from the Wikipedia article Typeface anatomy.
Fixed vs. variable
Many people generally find proportional typefaces nicer-looking and easier to read, and thus they appear more commonly in professionally published printed material. For the same reason, GUI computer applications, such as word processors and web browsers, typically use proportional fonts. However, many proportional fonts contain fixed-width (tabular) numerals so that columns of numbers stay aligned.