Q. Not actually a question but a comment on one of your recent answers, regarding type style for book titles on social media platforms. You left out a common and I think preferable option: to use leading and trailing underscores (e.g., _A Tale of Two Cities_). Some software (such as Slack and WhatsApp) already converts text with that form to italics, and readers will so understand it even on platforms (such as Facebook) that do not yet do so.
A. In our original answer, we were considering the problem of presenting book titles in a stylistically appropriate way on platforms that do not allow for italics. Literal underscores would be _overkill_ for most types of posts. Readers don’t usually need to know that, for example, Chicago recommends italics where this option is available. But you are right: where it is important to communicate italics as such, underscores (known in Unicode as low lines) would be the preferred approach (just as *asterisks* would be the preferred delimiters for boldface).