Italic has, in general, four uses:

1. for emphasis.
2. to set off a title, word, or passage from the context.
3. for running titles, sub-heads, the headings of tables, and other like places where something different from the text letter seems needed for variety.
4. for display purposes in commercial work.

One very important principle should always be observed in the use of italic for emphasis. Emphasis should always be used sparingly. Make the words do their work. Do not try to supplement poverty of thought and weakness of expression by italics, capitals, and other marks of emphasis. Where there is too much emphasis attempted no emphasis is secured. This fault was much more common formerly than now.

The accompanying reproduction of a page from a book printed in 1690 (place not given, but probably London) illustrates several of the faulty uses of italics common at that time. An entire paragraph is italicized (quite unnecessarily) for emphasis. All proper names and adjectives derived from them are italicized where they occur in the regular text and printed in roman where they occur in italicized passages. Note the frequent capitalization for emphasis and especially the italic capital with roman lower-case in the first line of the second paragraph. This is a frequent usage in this particular book. In this book all quotations are printed in italic without quote marks. The paper, composition, and presswork of the book are very poor. It represents English printing in its worst period.

Moderation in the use of italics is so important that in many cases the compositor is justified in ignoring markings for italic in his copy where they are too profuse. The author is often surprised and disappointed at the appearance of his proof when it comes back heavily italicized. Moreover the occurrence of many italics increases the cost of composition because of the greater labor involved.

I. Italicize, subject to the caution just given, any words or phrases which it is desired to emphasize.

II. Foreign words and phrases incorporated into English sentences are sometimes italicized and sometimes not so distinguished. The deciding element in fixing the usage in these cases would seem to be the commonness and familiarity of the word or phrase. For example, the meaning of bona fide (Latin), menu (French), recto (Italian), or stein (German) are as well known as those of most English words. To all intents and purposes these words have been adopted into our language. On the other hand, jeu d'esprit (French) or inter alia (Latin) would probably not be immediately understood by the casual reader. Words of the first type should not be italicized. Words of the second type should be.

Following is a partial list of words of foreign origin which should not be italicized even when the original accents are retained. It is better to retain the accents. They are, however, often omitted. Familiarity plays its part here also. DÉnouement is very often written without the accent; nÉe is rarely so written. The absence of accented letters from typewriters, from ordinary fonts of type, and from the matrices ordinarily used in type-casting machines probably contributes largely to their omission.

Following is a short list of words or phrases of foreign origin which are used occasionally but are not familiar enough to be printed in the text type.

The following words, phrases, and abbreviations used in literary and legal references should be italicized.

Do not italicize:

When an unfamiliar foreign word is used to convey precise description, put it in italic, but use roman for repetition of the word.

Italicize brief passages of foreign words which may be incorporated into an English passage but may not be long enough to be treated as regular quotations.

De gustibus non est disputandum, or as the French have it, Chacun a son gout.

Longer passages in foreign languages should be set in roman.

To set an entire paragraph of quoted matter in a foreign language in italic, or even to use italic too freely for phrases, practically nullifies the value of it as a display letter for the sub-headings or for any other part of the book in which distinction is really needed. Quotation marks, indention, smaller type, or any of the marks which distinguish quoted matter are sufficient.

III. At one time it was quite customary to set all quotations, whether in English or a foreign language, prose or verse, in italics, but that fashion is now happily obsolete. Some modern printers use italic for bits of verse between paragraphs in the text of roman, but it is a fancy and not likely to be permanent.

IV. Do not italicize foreign titles preceding names of foreign institutions or places, streets, etc., the meaning or position of which in English would call for roman type.

Pere Ladeau; Freiherr von Schwenau; the Place de la Concorde; the Museo delle Terme.

V. In text matter use roman for the name of any author, but italicize the title of the work. This applies to books, including plays, essays, cycles of poems, and single poems of considerable length, usually printed separately, and not from the context understood to form parts of a larger volume; pamphlets, treatises, tracts, documents, and periodicals (including regularly appearing proceedings and transactions). In the case of newspapers and periodicals the name of the place of publication should be italicized when it forms an integral part of the name, but do not under ordinary circumstances italicize the article the.

In many offices the names of papers, magazines, and serials are not italicized. Roman is often used without quotation marks, the title being indicated by capitalization. When such names are used as credits at the end of citations or notes they should always be italicized.

This is largely a matter of individual taste and office style. Ample warrant can be found for either form in the writing of the best authorities and in the practice of the best offices.

VI. In citations which make a full paragraph, and in footnotes, the name of both author and book are commonly set in roman lower-case. At the end of a paragraph or footnote specification of author and book may be roman for author and italic for book. When only the book is given, use italics.

These rules are often modified in long bibliographical lists, tables, or other cases when following them would cause a great accumulation of italics and spoil the appearance of a page. Do not italicize the books of the Bible (canonical or apocryphal) or titles of ancient manuscripts, or symbols used to designate manuscripts.

D16, M6, P, J.

VII. Italicize see and see also, in indices and similar compilations when they are used for cross-reference, and when it is desirable to differentiate them from the context.

VIII. Italicize for and read in lists of errata to separate the incorrect from the correct.

Page999 for Henry read Henri.

IX. The phrases prima facie and ex officio are sometimes used to qualify the nouns which follow, and sometimes used as adverbs. As qualifiers they are often printed in roman with the hyphen.

Prima-facie evidence.
An ex-officio member of all committees.

When used as adverbs they may be printed in italics without the hyphen.

The evidence is, prima facie, convincing.
The speaker is, ex officio, the chairman.

X. Names of ships, especially when they are taken from places, as in the United States Navy, are often italicized.

U.S.S. Philadelphia, U.S.S. Alabama.

XI. Names of paintings, statues, musical compositions, and characters in plays are sometimes italicized. This is not ordinarily advisable. It violates the rule of never using italics or other emphasizing devices needlessly and is liable to mar the appearance of the page. It is sometimes necessary, however, to avoid ambiguity. For example, Julius Caesar is a historical personage, "Julius Caesar" is one of Shakespeare's plays, Julius Caesar is a character in the play.

XII. Italicize the symbols a), b), c), etc., used to indicate subdivisions when beginning a paragraph and a, b, c, etc., affixed to the number of verse, page, etc., to denote a fractional part.

See Chap.iii, sec.2a).
Luke4:31b.

XIII. Italicize letters used to designate quantities, lines, etc., in algebraic, geometrical, and similar matter, and in explanation of diagrams and illustrations.

(a+b)²=a²+2ab+b²; the line a c=the line a b; the n^th power; at the point B.

XIV. Italicize particular letters of the alphabet when referred to as such.

We use a much more frequently than q.

XV. Authorities in science differ in the use of italics and capitals. In strictly scientific matter it is better to follow copy if the copy is intelligently prepared; if not, follow some recognized text-book on the subject.

In general the following rules will be found serviceable.

1. In botanical, zoological, geological, and paleontological matter, italicize scientific (Latin) names of genera and species when used together (the generic name being in the nominative singular), and of the genera only, when used alone. When genera and species are used together the genus always comes first, species second.

   Agaricus Campestris, Felis leo, Conodectes favosus, Phyteuma Halleri, Pinus, Basidiabolus, Alternaria, Erythrosuchus.

2. In medical matter the general practice is to print names of diseases and remedies in roman. In the Encyclopedia Britannica, Eleventh Edition, however, the scientific names of diseases are printed in italics.

3. In astronomical and astrophysical matter italicize:

   1. The lower-case letters designating certain Fraunhofer lines: a, b, g, h.

   2. The lower-case letters used by Baeyer to designate certain stars in constellations for which the Greek letters have been exhausted: f, Tauri; u, Hercules.

4. Italic should not be used for:

   1. Greek, Latin, and Arabic names of planets, satellites, constellations, and individual stars: Neptune, Thetys, Orionis.

   2. Symbols for chemical elements: H. Ca. Ti.

   3. Capital letters given by Fraunhofer to the lines of the spectrum: A–H, K.

   4. Letters designating the special types of stars: A5, B3, Mb.

   5. The capital letter H with different Greek subscript letters, used to designate symbols of hydrogen: H_a, H_b, etc.

   6. Designations of celestial objects in well-known catalogues; also the Flamstead numbers:

      M13 (for No.13 of Messier's Catalogue of Nebulae and Clusters), Bond619; N.G.C. 6165; B.D.-18°4871; 85Pegasi, Lalande5761.

      But when initials are used to express the titles of catalogues, as such, and not to designate a particular celestial object, such initials are to be italicized, following the usual rule of references by titles.

      B.D.; N.G.C.

XVI. In resolutions italicize the word "Resolved," but not the word "Whereas."

XVII. Italicize the names of plaintiff and defendant in the citation of legal cases; also the titles of proceedings containing such prefixes as in re, ex parte, In the matter of, etc.

The Boston Elevated Railway Co. vs. The City of Cambridge. In re Johnson; ex parte Thomas; In the matter of the petition of John Smith for a change of venue.

XVIII. Italicize address lines in speeches, reports, etc., and primary address lines in letters. Set the address flush, in a separate line, with the nouns capitalized.

Mr. Toastmaster, Ladies and Gentlemen.
Mr. HenryP. Porter, 148High St., Boston, Mass.

XIX. In signatures italicize the position or title added after the name. If this consists of only one word, it is usually run into the same line with the name.

FrederickW. Hamilton, Clerk. If the title consists of more than one word but is no longer than the name, center the first letter under the name line, and indent one em on the right.

JohnF. Fitzgerald,
Mayor of Boston.

If the title is longer than the name, center the name over the second line and set this flush:

MintonP. Warren,
Professor of Latin Language and Literature.

Sometimes a long title may be set in a smaller type, or, if this is not advisable, it may be put into two lines.

These rules are generally sound, but may have to be varied to suit special conditions.

Italicize the signatures of contributors to magazines, etc., when the names appear at the end of the article. If the name appears at the head of the article use small capitals, or, as is often done, the same type as the text.

XX. Italic may be used to distinguish the words or clauses which serve as verbal texts for an extended comment. In printed sermons, for example, the text is often set in italics.

XXI. Italic may be used with good effect for running titles, for table headings, and for sub-heads. It is not desirable for side notes. It has many kerned letters which are liable to break off at the ends of the lines in an exposed position.

XXII. In the English Bible italics are used to print words which are not expressed in the original Hebrew or Greek but are implied in the original and expressed in the translation.

Their quiver is an open sepulchre; they are all mighty men.

I find in him no fault at all.

These italics should never be mistaken for marks of emphasis.

XXIII. Care should be taken that the italic type used should mate well with the roman. The fact that it often did not so mate, even in fonts supposed to go together, was one cause for the disfavor which came to attend its use. Typesetting machines constructed without proper provision for the composition of italic have been very influential in restricting its use. Italics are now practically abolished from newspaper work except in advertising matter, though they were used in newspapers to excess in the eighteenth century.

XXIV. Italics are indicated in manuscript by drawing a single line under the words to be so printed.