There are about seventeen punctuation marks in common use in prose: . , ; : ? ! ' " - ( ) ‘ ’ “ ” – and —. The nine simplest will be covered in this post.
The period and the comma
- The period is basically the same as the tittle (dot) on the ‘i’, though often slightly larger.
- Periods and other very small baseline-dwelling punctuation marks require padded sidebearings so that they are legibly distinct from the letters before them. Their sidebearings are twice as wide as a typical rounded letter’s.
- Periods sit on the baseline, with a very small undershoot.
- The comma is a period with a tail. The tail extends about one period-height below the baseline.
- The head of the comma is usually a bit thinner than the period, since the comma is longer. It is also a good idea to have the head of the comma be somewhat evocative of the terminals in its typeface.
Colons and semicolons
- Colons and semicolons are pretty straightforward to design. The colon is a period with an extra dot floating just below the mean line, and the semicolon is a colon with the lower dot replaced with a comma.
- It’s a common misconception that the colon is written with the bottom dot floating above the baseline. This form is a similar but distinct glyph called the raised colon, and is only to be used between capital letters and numbers (alternatively, some fonts have vertical kerning that raises the colon in an uppercase or numerical context, like Apple does in iOS). The lower dot of a regular colon sits right where the period goes.
- The upper dots of these glyphs lie very close to the mean line; they are not found floating in the middle.
Straight apostrophes and quotation marks
- The straight apostrophe and quotation mark are incredibly simple to design. They are just tapered rectangles that extend from the capital line down to about five-sixths the way to the mean line. The top of the straight apostrophe is always wider than the bottom.
- The quotation mark is simply two apostrophes combined into one glyph. Leave a space of about one apostrophe-width in between them.
- Apostrophes have very thin sidebearings to avoid making unsightly gaps in contracted words like “it’s”.
- In an ideal world, these glyphs would never be used. There is almost never a case where an experienced typographer would use straight apostrophes or quotes, except when typesetting literal computer code. Except when denoting minutes and seconds (or feet and inches—like 6′ 2″ ), these glyphs should always be replaced with curly quotes ( ‘ ’ “ ” ). Minutes and seconds should be written with the proper prime characters ( ′ ″ ).
Hyphens
- A hyphen is a simple rectangle. It should be a bit shorter and a bit thicker than the crossbar on the ‘f’.
- Hyphens, like colons, live centered between the baseline and mean line, not the baseline and capital line. They should be about as high up as the cross in the ‘x’.
- Spacing-wise, hyphens are padded more than you’d think. Side bearings of over 45/1000 ems are appropriate.
Parentheses
- Of all the punctuation characters discussed in this post, parentheses are probably the hardest to design. They are approximately 90 degree arcs that taper at the ends.
- Parentheses extend from the ascender line down to about two-thirds the way from the baseline to the descender line.
- While parentheses have stress (highly exaggerated—it cannot be reproduced with any broad-nibbed writing instrument), they are almost always perfectly symmetrical vertically (ie stressed didone-ly). Some very old style typefaces give them diagonal stress though.
