Proportional font

A font where glyphs are displayed using varying widths is considered a proportional font. Proportional fonts are "prettier" and thus run rampant in the typical GUI word processor or web browser. Proportional fonts can however make it difficult to format text in columns, or indent properly, and they typically look horrible in a terminal window. In such cases, a non-proportional font is preferred.

Comparison:

The two lines of text in non-proportional font (should) display as equal width, while the two lines in proportional font are radically different widths. This is because wide characters' glyphs (WQZMDOHU) get more screen width and narrow characters' glyphs (itl[]1|I) get less when using a proportional font.