(underlining as a punctuation mark)

Underlining's a line that is under,
A sort
Of a floor that's supporting a word.
Long or short,
Or to tightrope a word that seems to walk,
And no botching.
All eyes are upon it, and everyone's watching.

Underlining is the thing to use to suggest
That's this word
Or that word's
The word to be stressed,
Or to show it's a title,
Like Better Expression,
But it can be—like dashes—
A writer's obsession.
Too much underlining, all over the place,
Will often bring lines to the poor reader's face.

So though it is useful and though it is fun,
Be sure underlining
Is not overdone.

—This poem is compiled from On Your Marks, A Package of Punctuation
by Richard Armour; McGraw-Hill Book Company; New York; 1969; page 37.

For other marks of punctuation, go to this Index of Punctuation Marks unit.