“If I’m mak­ing a PDF that will prob­a­bly be read on screen, shouldn’t I use a screen-op­ti­mized sys­tem font?” No. In Win­dows, fonts are op­ti­mized for the screen us­ing hint­ing, which is ex­tra soft­ware code stored in the font it­self. Win­dows re­lies on this hint­ing when it draws text on screen (e.g., in Mi­crosoft Word, or in a web browser).

But Adobe Ac­ro­bat—what most peo­ple use to read PDFs—draws text on screen us­ing its own tech­nol­ogy. So in PDF, sys­tem fonts lose their screen-leg­i­bil­ity ad­van­tage over other fonts. Any PDF could also end up be­ing printed. There­fore, as a rule, you’re bet­ter off us­ing print-op­ti­mized fonts for PDFs, re­gard­less of how you ex­pect the PDF to be read.

“But if I use a print-op­ti­mized pro­fes­sional font in my PDF in­stead of a sys­tem font, my read­ers prob­a­bly won’t have the same font in­stalled.” Right. But it doesn’t mat­ter. When you gen­er­ate a PDF, your fonts are em­bed­ded in the PDF to pre­serve the formatting.

This is not true, how­ever, on the web. Web browsers use the text ren­der­ing of the op­er­at­ing sys­tem. Thus, in Win­dows browsers, screen-op­ti­mized sys­tem fonts have tra­di­tion­ally held an ad­van­tage, be­cause they look good and they’re al­ready in­stalled. (In­deed, the Mi­crosoft fonts Geor­gia and Ver­dana were specif­i­cally cre­ated for web use.) But this ad­van­tage is rapidly fad­ing with the ad­vent of screen-op­ti­mized web­fonts and the gen­eral shift to­ward higher-res­o­lu­tion screens. Still, for now, us­ing pro­fes­sional fonts on a web­site re­quires a lit­tle more leg­work than it does in PDF.

My aver­sion to Comic Sans—king of the goofy fonts—prob­a­bly comes as no sur­prise. But why Ar­ial? Ar­ial was cre­ated as a Hel­vetica sub­sti­tute. To many, they’re indistinguishable.

But to ty­pog­ra­phers, Ar­ial con­tains none of the con­sis­tency and bal­ance that makes Hel­vetica suc­cess­ful. For in­stance, the ends of the low­er­case a, c, e, g, s, and t in Hel­vetica are ex­actly hor­i­zon­tal. In Ar­ial, those ends are sloped ar­bi­trar­ily. Read­ing Ar­ial is like try­ing to have din­ner on a tippy restau­rant table.

As a sys­tem font, Ar­ial has achieved ubiq­uity akin to Times New Ro­man. And like Times New Ro­man, Ar­ial is per­ma­nently as­so­ci­ated with the work of peo­ple who will never care about typography.

You’re not one of those peo­ple. So use one of the fonts listed in Hel­vetica and Ar­ial al­ter­na­tives. Or use some­thing com­pletely dif­fer­ent. But don’t use Arial.