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Punctuation is the use of symbols (punctuation marks) to add meaning or clarify written language. Punctuation marks don't correspond to sounds, but may indicate where to leave pauses when reading text aloud.
Commonly-used punctuation marks
Full stop [.]
The full stop or period, also called a full point, is the punctuation mark commonly placed at the end of sentences. A period consists of a small dot placed at the end of a line of text.
The period is also used after abbreviations, such as Mr., Dr., Mrs., Ms. If the abbreviation is ending a sentence the second period is not needed unless the sentence ends with a question or exclamation mark.
The comma is used to mark off separate elements in a sentence: introductory clauses, words in a series, parenthetical phrases, or interjections. Commas are also used to separate items in lists, and to present large numbers in a more readable form.
These formal uses frequently also indicate a pause in speech. Writers often use optional commas for stylistic reasons, to indicate such a pause where none may be required, grammatically.
The comma is also used to separate two independent clauses (a group of words that can function as a sentence) that are joined by a co-ordinating conjunction ("and" & "but" when they are used to connect), eg:
An important, often misunderstood use of the comma is for thought interruptions. Information that is unnecessary to the meaning of the sentence must be set off and ended by a comma. If the information is necessary, no commas should be used.
In English, the semicolon has two main uses:
There are several rules that govern semicolon placement:
Some experts will allow for a semicolon to separate independent clauses that are joined by coordinating conjunctions when the clauses have internal commas that might lead to misreading:
Semicolons are always placed after closing quotation marks and are never followed by an uppercase letter, unless that letter begins a proper noun.
Colons are commonly used to introduce lists, or to connect a broad idea with a specific example: two related sentences can be separated by colons instead of full stops or semicolons. Colons may also be used to introduce a direct quote, or to draw attention to an appositive (a noun phrase that generally follows, but occasionally precedes, another noun phrase and renames or describes it). In any of these cases, a colon can only be used if the clause preceding the colon is independent.
In American English colons are also used after the salutation in a formal letter, Dear John:
When closing quotation marks and colons are adjacent, the colons always follow. Capitalization following colons is optional.
An apostrophe is commonly used to indicate omitted characters as in:
An apostrophe is used with an added s to indicate possession, as in Oliver's army, Elizabeth's crown. If a name already ends with an s the extra s is sometimes dropped: Jesus' parables.
An apostrophe is used by some writers to form a plural for abbreviations and symbols where adding just s rather than ’s would be ambiguous, such as mind your p's and q's. It is not necessary where there is no ambiguity, so CDs not CD's, videos not video's, 1960s not 1960's, 90s or '90s not '90's.
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