Semicolons, Colons, and Dashes
Semicolons
Use a semicolon to separate two related independent clauses (clauses that can stand as sentences on their own) that are not linked by a comma and coordinating conjunction (and, but, for, nor, or, yet, and so).
Use a semicolon to separate two related independent clauses linked by an adverb (however, therefore, nevertheless, etc.).
Use semicolons to separate items in a complex series.
A complex series contains internal punctuation. Semicolons help to clearly mark the break between each item in the series.
Do NOT use a semicolon between an independent and a dependent clause (one that cannot stand as a sentence on its own).
A comma is the appropriate punctuation between a dependent and independent clause.
Semicolons go outside quotation marks.
Colons
Use a colon to introduce a list.
The clause preceding the colon must be an independent clause. A colon should not separate parts of speech that naturally go together, such as an infinitive and its object (see below).
Use a colon to introduce an appositive (a phrase used to describe or define a noun).
Use a colon to set off a second independent clause that modifies the first.
Use colons to introduce quotations after an independent clause.
Use a comma when introducing quotations after a dependent clause.
Use colons in titles.
Use colons in business letters and memoranda.
In business letters and memos, colons are used in salutations (Dear Mr. Soandso:) and in memo headings (To:, From:, Date:, Subject:, Dist:).
Use colons in numbers and addresses.
Colons are used for Biblical citations to separate chapter from verse (Mark 4:12), in clock times to separate hours from minutes (8:56 a.m.), in ratios (4:1), and in website addresses (http://www.sparknotes.com).
Dashes
A dash is typed as two hyphens. There should be no space between a dash and the words on either side.
Use dashes to highlight extra informational comments.
Use dashes to set off important or surprising points.
Use only one dash or pair of dashes per sentence.
Reference: Strunk, Wiliam Jr., and E. B. White. The Elements of Style. 4th ed., Allyn and Bacon, 2000.
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