Underlining is used as a way of laying stress to a certain word of phrase.
This is the most important day of my entire life!
Dear diary, I’m never going to speak to George ever again!
Though it is rarely seen in the context of regular print media these days, underlining still remains the most popular and the easiest way to quickly emphasise something when using pen and paper.
However, in a digital world already containing bold and italics, not to mention CAPS, do we really need yet another emphasising tool in our typographical arsenal? I would argue not. Underlining often looks clunky and damages the otherwise crisp look of a font.
When writing narrative prose, I personally would never resort to underlining. Instead, I would use italics to convey my meaning. For example:
‘She would never ever do anything of the sort!’ her mother declared.
What had he expected, that she would rejoice upon hearing his confession?
Though I have never used bold in narrative prose beyond beefing up the appearance of my chapter titles, bold can be used in other forms of writing, such as articles or blogs. The advantage of using bold is that, due to its very nature, it stands out among regular text. For example:
This is when you should never use a comma.
In situations such as this, the apostrophe comes after the ‘s’.
So while underlining has become quite obsolete in the context of written prose, it is still used widely on the Internet to suggest that a certain word or phrase is a hyperlink. I personally prefer the more modern technique of making the link a different colour, however. For example:
This is a link to my short story The Witch Hunt.
So while underlining is declining as a necessary tool in the digital and printed world, I believe it will remain alive and well in the realm of quickly scribbled notes to parents, jotting down details on the notepad beside the phone, in corporate reports and in the on-paper editing world.
The day teachers stop underlining things in red pen, the sun will rise in the west!