Recently I was asked this question; What is the use of oblique text in typography and how to not use it?
The difference between Italics typeface and Oblique text it is a difficult distinction to understand and not a quick easy answer.
The simple answer is don't use oblique text to create professionally set type.
In typography that means only use type-set in “true-drawn” Italics. Type not made slanted or oblique with a program on your computer, such as Word. With many word processing or text editing applications you can create computer-generated slanted versions or oblique text based off their Roman companions.
Oblique vs Italic is a subject of some depth.
For this answer I am calling Obliques the slanted versions of their Roman companion with no major design differences.
Italics typeface of professional quality then, are hand-drawn, or very skillfully modified to optically correct the distortion that results from angled design. Italics have different design characteristics. They are more than a typeface that is angled to it’s upright companion typeface. Italics are a complementary design similar, but in a different way to a book, bold, black, or light typeface family weight version. In some Itlalic versions you can see a calligraphic appearance, often those designed for a serif typeface family. A san serif Italic may only have a few characters that have differences. The lower case a is different as an example in Myriad Italic.
It gets sticky when the word Oblique is used as this to many typographers of 30 plus years in setting type means fake versus true italics. The terms Oblique and Italic like Font and Typeface are loosely used. It is no wonder so many are confused as typefaces are sold with the word oblique in the typeface name.
In the time before computers and typewriters, handwriting was used. In something like a handwritten manuscript certain markup was universally used to indicate the written copy (content) mechanics and punctuation. Other correction marks were used, placed in margins to indicate usage, spelling, grammar, general effectiveness by editors, art directors, proofreader’s communicating to the printer and typesetter. Eventually a standard set of symbols were used to convey instructions to the typesetter called Proofreader’s Marks.
I tell you this because over time Italic type has taken over many of the functions previously performed by quotation marks. Eventually as typewriters came into use to prepare manuscripts Italics were indicated to typesetters by a single straight line underlining each word to be italicized on the typewritten page. Still today, Italics are indicated in typewritten or handwritten manuscript by underlining.
As to use,
Italics are used to designate;
1. TITLES OF SEPARATE PUBLICATIONS.
- Magazines and Newspapers
- Musical Productions
- Plays, films, and Broadcast Programs
- Long Poems
2. NAMES OF SHIPS, TRAINS, AIRCRAFT.
3. TILES OF PAINTING AND SCULPTURE.
4. FOREIGN WORDS, NOT YET ANGLICIZED.
5. WORDS, LETTERS, FIGURES, OR SYMBOLS REFERRED TO AS SUCH
6. EMPHASIS, WHERE IT CANNOT BE CONVEYED BY THE ORDER OR CHOICE OF WORDS.
“You are so right,” she remarked. [Only italics will convey the speaker’s oral emphasis.]
There are many rules, and my above list is brief. You can get in-depth reference and explanation from finding Handbooks of English about style, usage and grammar or use something like The Chicago Manual of Style.
Typesetting is done after a graphic designer or art director have carefully considered context, purpose, audience and more. The typeface family is then selected or may be specified by brand guidelines.
When setting type the client, required or not, will send me a printed copy sheet and this has notes and proofreader marks. I also get an accompanying text or word file to use. For some projects I generate this written copy, as I am both Art Director and Copywriter for a client. Point is copy needs to go through drafts and proofing, markup. Then is typesetting. Good writing and typesetting require human massage.
When you see a word underlined with a single straight line, use the true Italic typeface, never a fake Oblique version.
To learn more and get visual written examples there is a good article by Mark Simon on Fake vs. True Italics. Go to this url into your browser