Q. On social media platforms, where italics are not an option, what do we do with book titles or other titles that would normally be italicized?
A. You have three choices: (1) Let the capital letters speak for themselves: Main Title: Subtitle. (2) Use quotation marks: “Main Title: Subtitle.” (3) Use all caps: MAIN TITLE: SUBTITLE. The first option is the cleanest but doesn’t do a good job especially with one-word titles; the second and third options will delimit the title more definitively. The third option, favored by some publishers (like @RandomHouse), is a convention that dates to the era of typewritten editorial memos (try underscoring titles on a manual typewriter all day long). Quotation marks are maybe the most sensible option, but there’s no settled convention. Choose your favorite and stick with it.