What’s the proper way to display the title of a book on a Web page? The traditional method of underlining makes it confusing for Web users, who expect an underlined word or phrase to be a hyperlink. Should the title be bolded? Italicized? What about quotation marks?
A lot of underlining of book titles is used in bibliographies for scholarly works, but other than that, it’s not done much on the Web. Or shouldn’t be. And it’s not used in the print world much, either. Underlining was initially used to tell the typesetter to put specific text in italics.
The latest style guides say to use italics for titles of books, films plays, and long poems, works of art, periodicals, etc. One of my favorite online style guides is The Web Content Style Guide by McGovern, Norton, and O’Dowd (2002). Another is The Yahoo! Style Guide. I recently downloaded it to my Kindle, and it is excellent.
Chicago Manual of Style, 16th Edition (2010) says (8.166) that when quoted in text or listed in a bibliography, titles of books, journals, plays, and other freestanding works are italicized and capitalized headline style. CMS also says (8.161) that titles of articles, chapters, and other shorter works are set in roman text and enclosed in quotation marks.
Here are a couple of resources that address this issue: Using Italics and Underlining, and Polished Presentations.