Ooooooh, my pretty! My PWECIOUS!!!
And so the horror begins...the moment when an author decides that s/he is going to use one of the gorgeous fonts "freely" (pay attention, now) available to him/her on their computer...whether it's in Apple's "Font Suitcase" or in Microsoft Office's Word program (or any of the other various and sundry word-processing programs). And so--as is the case in a manuscript (for both print and digital conversion) that I received today, I have an author using not one, but three copyrighted fonts, those being AR Julian, (a Times New Roman look-alike), Copperplate Gothic Bold and my personal favorite, "Final Draft Courier," which isn't merely a copyrighted font, but it's a copyrighted font inside a copyrighted piece of software (just like the others). OH--I nearly forgot--and Calibri, (a fourth!) another perennial authorial favorite and, yes, you guessed it, licensed-to-Microsoft, not you, font.
When I tell authors that they have to either license those fonts, or find Open Source alternatives, I'm always regaled with vituperative hate mail or angry phone calls, as if I'm trying to torture the writers, or make them jump through hoops for my own amusement.
What I am trying to do, however, is to protect the intellectual property of someone else--the font designer. Moreover, I'm trying to protect the author from getting a cease-and-desist letter, at best; or a demand for royalties/licensing fees, at worst, from the original licensor of the font. Just as I wouldn't give away the copyrighted property of our authors, I won't knowingly use a font that's been licensed by Microsoft (or Apple) for your personal use only--not for redistribution, which is "for sale," which means: use in a book, print or otherwise, being sold.
How do you know if a font is copyrighted? One easy way is to cruise Fonts.com, or Whatdafont.com, and give Free-fonts-ttf.com a try; but the safe bet, given US law, is that if you can't explicitly determine that the use of a font is free (or Public Domain or Open Source) is that it is copyrighted. In the US, just like your book, the font is copyrighted upon creation. Just like your book, it can't be used (sold) without express permission. A quick check on the fonts mentioned above shows that AR Julian seems to be MIA (Missing in Action)--so I've told my client to find a substitute. Copperplate Gothic is a $200+ font package; (a sans-serif font with some serif overtones, in all caps) he can license it or find a really undetectable substitute on FontSquirrel.
Our friend Calibri can be licensed for a mere $35; but "Final Draft Courier" is in the wind--and given that Courier has been in the Public Domain for my lifetime, I'd recommend to the client that he just use a basic Courier font.
So, remember: The Best Fonts in Life Are Free. ;-)
But--what does "free" really mean? "Free," in Open-Source terms, means "freely copyable, useable and changeable," not necessarily "free of ANY cost." Many, if not all, "open source" fonts have either small licensing fees, or require credit lines in your books. Don't confuse the Darknet--pirated works--with Open Source, and don't assume that Open Source means FREE of any licensing fees. Any time you pay for Creative Commons or Open Source (or even Public Domain) "stuff" you're paying for something else: bundling, delivery, maintenance, etc. The content itself is free (France uses the term, "libre" for this type of usage, which is, as Our Man in Oahu, Rick, pointed out, a nice cross-lingual pun. I should in fairness tell you that he wrote most of the last two paragraphs.)
So, distinguish the difference like the Open Source guys do, and remember this when picking your fonts:
Free as in speech, not Free as in beer.