Because italic (sloping) type contrasts with roman (vertical) type, a writer can require words or passages to be typeset in italics in order to call special attention to them, to give them special meaning, or to distinguish them from the rest of his or her text.
Use italics sparingly, or they lose their effectiveness.
When an entire passage is printed in italics, the punctuation (including parentheses) and any numbers (including footnote references) will also be in italics. If just a word or phrase is in italics, only the punctuation proper to it is printed in that typeface.
Note that when the main body of a text is printed in italics, roman type is used for emphasis and for the other purposes described in this chapter.
Italics can serve to indicate emphasis in the following cases:
What differences might we expect to see in human behaviour if honesty were shown to be the worst policy?
I did not say we would go: I said we might go.
Why was he chosen to chair the committee?
Write these in italics if they are not considered to have been assimilated into English. A non-English pronunciation often indicates that a word or phrase has not been assimilated. Many such terms occur in legal, political and musical contexts:
When French or foreign words or phrases are considered to have been assimilated into English, italics are not used:
Most dictionaries do not indicate which words or phrases are to be italicized. Among those that do are The Concise Oxford Dictionary, The Random House Dictionary and the Collins dictionaries, but they are not always unanimous. Consult the Concise Oxford but also exercise your own judgment, with due regard for the type of text and intended readership. When in doubt, use roman type.
If an unfamiliar French or foreign term or phrase is used repeatedly in a text, it should be italicized at the first occurrence and accompanied by an explanation. Subsequently, it may be set in roman type.
Although there is a growing tendency to print Latin reference terms and phrases in roman type (especially when abbreviated), many are still italicized:
Do not italicize the following:
Italicize the titles of books, pamphlets, published reports and studies, plays, operas and long musical compositions, paintings, sculptures, novels, films, long poems, newspapers and periodicals:
For the title of a major work within another title, two possibilities exist:
Titles of scientific periodicals are usually abbreviated and set in roman type (see 9.08 Compiling a bibliographic entry(c)).
Do not italicize unofficial titles:
Titles of articles, short poems and short stories, songs, arias and other short musical compositions, and radio and television programs are set in roman type and enclosed in quotation marks:
In legal texts italicize the names of statutes and court cases:
Do not italicize short forms such as "the Act" or "the Charter."
See also 6.10 Identifying matter.
Italicize the names given to individual ships, spacecraft, aircraft and trains but not articles, etc. preceding them:
In Department of National Defence documents, names of ships are written entirely in upper case and are not italicized:
These should be italicized:
Quotation marks (see 8.11 Reference to words as such), boldface type and underlining may perform the same function.
Italics may be used to set off peripheral matter such as prefaces and dedications or epigraphs and quotations at the beginning of a book or chapter. Stage directions for a play are usually set in italics and placed within brackets or parentheses. Introductory matter setting the scene is also usually in italics, but not in brackets or parentheses.
Italicize the terms See, See under, See also and See also under when used in indexes, and the expressions To be continued, Continued on p., Continued from p. and Continued on next page.
Italicize editorial clarifications:
Italicize the scientific (Latin) names of genera and species in botanical, zoological and paleontological matter:
Do not italicize the names of the larger subdivisions (phyla, classes, orders, families and tribes):
Italicize letters designating unknown quantities and constants, lines, etc. in algebraic, geometric and similar matter:
Note in the second example that no space is left between the numerical coefficients and the variables, and that the italics help to differentiate between the variable x and the multiplication sign. Correct spacing and italic type also help to distinguish between algebraic variables and SI/metric symbols:
Italicize quantity symbols such as l for length, m for mass and v for velocity in order to distinguish them from unit symbols such as "L" for litre, "m" for metre and "V" for volt, which are normally printed in roman type:
Italicize Latin prefixes and Greek and Roman letters used as prefixes to the names of chemical and biochemical compounds:
A number of Greek and Roman letters used in statistical formulas and notations are italicized:
Headings or subheadings of a document may be italicized in order to clarify its arrangement for the reader. See 11.16 Headings for further information.
An example of an italicized run-in sidehead can be seen in 7.07 Other uses.
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TERMIUM Plus®, the Government of Canada's terminology and linguistic data bank
Writing tools – The Canadian Style
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