Italics and Underlining
Sometimes you want your reader to pay particular attention to a word or phrase; in informal or creative writing, you can use different colors, different fonts, unconventional capitals – the options are endless. Not so in formal writing. Visually drab, formal writing has a lot of rules which do not lend themselves to creativity; the writer is limited to punctuation, italics and underlining to draw the reader’s attention to certain areas.
Most of the time, we just use italics now. Computers have made it simple to highlight a word or phrase and change it from normal to italics. Of course, the conventions of underlining still persist from the not-so-long-ago days when typewriters and handwriting were the norm (writing in italics is beyond the ability of the average person, and adding italics keys to a typewriter is expensive and unwieldy). Each formal writing format has its own rules for titles, etc. so you’ll need to check the fine details before you actually do the italicizing or underlining.