The system fonts Courier, Menlo, and Consolas are examples of
The samples above are set at the same point size. But the monospaced font (first and third rows) takes up more horizontal space than the proportional font (second and fourth rows). The differences are most noticeable in characters that are narrow in the proportional font (like f i j l r t) and the punctuation characters.
Monospaced fonts were invented to suit the mechanical requirements of typewriters. They were not invented to win beauty contests. Compared to proportional fonts, monospaced fonts are harder to read. And because they take up more horizontal space, you’ll always get fewer words per page with a monospaced font.
In standard body text, there are no good reasons to use monospaced fonts. So don’t. Use proportional fonts.
If you practice in one of the few courts that require a monospaced font, you can still do better than Courier. See font recommendations for better options.