Common Punctuation Marks And How To Use Them

A discussion of each mark follows, in alphabetical order by name of mark. Also includes how to divide words; use of numerals/numbers; possessives; and common errors in punctuation.

Apostrophe (‘) is used to indicate possession, contractions, and plurals.

    1. Possession:
      • The possessive form of singular nouns ends in ‘s, including nouns ending in s, x, z, ch, or sh. For example: a dog’s life, a lass’s smile.
      • The apostrophe follows the s for the possessive of plural nouns except for plurals which do not end in s. For example, you would write: zebras’ stripes, but children’s books.
      • No apostrophe is used for personal pronouns like “hers,” “its,” “theirs;” indefinite pronouns require one: e.g., one’s friend.
      • In compounds, the ‘s is added to the word nearest the object of possession.
      • Joint possession is shown by putting the apostrophe on the last word of a series, e.g., Abelard and Héloise’s child.
      • The apostrophe follows the s of a word with two sibilant sounds; e.g., Kansas’ and Moses’.
      • The apostrophe is not used in “Pikes Peak,” the mountain in Colorado.
    1. Contractions: The apostrophe is used when leaving out a letter or number in a contraction. For example, “I can’t” (instead of “cannot”); “let’s dance” (instead of “let us”); “it’s a beautiful day in the neighborhood” (instead of “it is”).
  1. Plurals:
    • Plurals of letter abbreviations with periods and single letters use ‘s. For example: There are four s’s in .
    • Plurals of letter combinations, numerals, and hyphenated nouns end in I with no apostrophe; for example: 1s and 0s.
    • The apostrophe is not used in names of organizations unless actually part of the legal name.

Braces ({ }) are used to show the relationship of elements in a group.

Brackets ([ ]) are used to insert words in quoted matter, for explanatory, correctionary, or commentary reasons.

  • Used to insert missing letters and to enclose insertions that take the place of or slightly alter the original text, e.g., [they] may replace a long list of names previously mentioned. Brackets are also used in unquoted matter for the same reasons.
  • Used as parentheses within parentheses.
  • Used in mathematical expressions (to show matter to be treated as a unit), chemical formulas, and for phonetic symbols.

Colon (:)

  • Used to introduce explanatory information, lists; for salutations, as in “Dear so-and-so:” and in clock time “It was at 5:00 in the afternoon”; periodical reference (e.g., 4:3); and between book title and book subtitle (e.g., Dictionaries: The Art and Craft of Lexicography).
  • Used before a final clause that explains, or amplifies something in that sentence, e.g., The dissertation needs work: it lacks flow.
  • Introduces a series or summarizing statement (e.g., The following is on our list of places to go: grocery store, toy store, doughnut shop. /She had one great love: him.)
  • Used in proportions, e.g., 2:1, and as a ratio sign, e.g., 1:2::3:6.
  • May introduce a quotation, especially a long one.
  • Used in dialogue text, e.g., Juliet: O Romeo, Romeo! Wherefore art thou Romeo?
  • Used in correspondence for headings and introductory terms (To: From: Re:) and to separate writer/typist and carbon-copy abbreviation from the recipients.

Comma (,) is most commonly used to separate or set off items that might otherwise be misunderstood, such as:

  • Members of a series used with “and,” “or,” or “nor.”
  • Main clauses, or before the conjunction in a compound sentence.
  • Two verb phrases in a sentence.
  • Subordinate clauses/phrases within sentence.
  • An apposite (noun referring to previous noun, e.g., my sister, Nancy) or contrasting words/phrases (e.g., I need you, not anyone else.)
  • Introductory items, e.g., Sir, are you listening?
  • Interrupting or parenthetic items.
  • Before quotation following an introductory phrase, e.g.: She said quietly, “I love you.”
  • Inside a closing quotation mark, e.g.: I said “wash,” not “drawer.”
  • To show omission, e.g., The thing is, we need time.
  • Between compound qualifiers, e.g., He has big, broad shoulders.
  • Between name and title, title and organization, name and degree, surname and Junior/Jr./Senior/Sr.
  • In an inverted name, e.g., Shakespeare, William; Kipfer, Barbara Ann.
  • To separate thousands, millions, etc. in number of four or more digits, e.g., 2,000.
  • To set off the day of the month, e.g., Their anniversary is June 1, 1991, when they met.
  • To set off elements of an address, e.g., Write to him at The Language Centre, University of Exeter, Exeter, England EX4 4QH.
  • After the salutation in informal correspondence, e.g., “Dear T.B.,” and after the complimentary close in all correspondence, e.g., “Respectfully,”.

Dash (–)

  • Used to denote a sudden change or break in a sentence, e.g. He was gone — heaven forbid — for an hour and no one knew where he was. No spaces are added before or after a dash and do not combine with a colon, comma, or semicolon.
  • As a substitute for parentheses or commas in an attempt to clarify meaning or place emphasis, e.g., She has this to accomplish today — work, study, cook, and household duties — as well as take care of her child.
  • Before an amplification, definition, explanation, or summary statement, e.g., To be or not to be — that is a question we each ask ourselves at night before we turn out the light.
  • At the end of an unfinished word or sentence, e.g., The story went on to say that–.
  • To precede an author’s credit for a quotation and as a way of setting off something in page design, as for lists, outlines.
  • The en dash is used in typeset material and is shorter than the em dash, which is represented in typewritten material by two hyphens. It is used as a replacement for a hyphen when the meaning intended is ‘up to and including’, e.g., “1987-91,” “Monday-Saturday.” A two-em (four hyphens) dash is used to show missing letters in a word. A three-em (six hyphens) dash is used to show that a word is left out or that an unknown word or number is to be supplied.

Division of words: Guidelines for dividing words at the end of lines are:

  • Pay attention to the way the word is pronounced (syllables) and do not break the word so that it would be mispronounced or misunderstood.
  • Divide between doubled consonants, except when it would divide a simple base form, e.g., “re-com-men-da-tion,” but “sell-ing,” “buzz-er.” When the doubled consonant comes before -ing, the second consonant stays with the -ing.
  • Do not divide a one-syllable word, even if there is an inflected ending like -ed‘, e.g., spelled, bummed.
  • Do not divide a word so that one or two letters is left either at the end of one line or the beginning of another. Division after a prefix, putting it at the end of a line, is permissible.
  • Do not divide words of six letters or less.
  • Divide hyphenated words at the hyphen.
  • Do not divide before the following suffixes; they should not be at the beginning of a line alone nor should they be divided themselves: -able, -ceous, -cial, -cion, -cious, -geous, -gion, -gious, -ible, -sial, -sion, -tial, -tion, -tious.
  • When a vowel alone forms a syllable in the middle of a word, keep it with the previous syllable, e.g., physi-cal.
  • A liquid or silent l syllable at the end of a word or part of an inflected ending should not be put on the next line alone, e.g., read-able, twin-kling.
  • Proper nouns, numerals, and abbreviations should not be divided.

Ellipsis points or ellipses or points of ellipsis or suspension points (…)

  • Used when words are omitted: three periods in the middle of a sentence, four at the end of a sentence (unless the sentence ends with a question mark or exclamation point: then it is “…?” “or ‘…!”).
  • May also indicate a break or suspension in speech.
  • Punctuation that normally falls before or after the ellipsis points can be retained for clarity; a space precedes and follows ellipses.

Exclamation point (!)

  • Used to show surprise, incredulity, praise, a command — to show force in statement.
  • May be used to replace a question mark when irony or an emphatic tone is meant, e.g., How could you!
  • An exclamation point and question mark may be used together to show extreme force.
  • If the exclamation point ends a sentence in a quotation, the comma or period is dropped.

Hyphen or (-):

  • Used to connect the elements of some compound words, especially ones of three or more words.
  • Used to divide a word at the end of a line.
  • Used in fractions and compound numbers.
  • Found in measurements with numbers and unit.
  • Used in ages with number and unit.
  • Used in prefixed words when a vowel is doubled or consonant is tripled.
  • Used for certain prefixes such as ex-.
  • Used to make a word clear from its homonym (“recover” and “re-cover”) between a prefix and the second word if it is a proper noun and proper noun compounds.
  • Used for certain suffixes such as -elect.
  • Used for compounds which begin with a single capital letter, such as H-bomb.
  • Used for compound adjectives, including those where the first adjective ends in -ly, as in “scholarly-written piece” (but not for compound modifiers of adverb-and-adjective, such as “widely known author”).
  • Used for directions, such as: north-northwest.
  • Used for words spelled out letter-by-letter, as in “y-e-s.”
  • Used to show stuttering speech.


  • The most common, Arabic numerals, are 0, 1, 2, etc.
  • Roman numerals use the letters I (1), V (5), X (10), L (50), C (100), D (500), M (1,000) and are used to designate certain wars (WWI, WWII), sequence in family, rulers, vehicles, major headings in documents.
  • Cardinal numbers are 0, zero, 1, one, etc.
  • Ordinal numbers are 1st, first, 2nd, second, etc.
  • In general, write out the first nine cardinal (1-9) numbers (except for address numbers 2-9, dates, decimals, game scores, highways, latitude/longitude, mathematical expressions, measurement/weight, money/financial data, percentages, proportion, scientific expressions, statistics, technical expressions, temperature, time, unit modifiers, votes, and numbers not written out in a proper noun) and any number that begins a sentence; use figures for 10 and above.
  • The first nine ordinal (1st-9th) numbers are usually written out, especially when describing order in time or location.
  • Governmental, political, and military units numbering one hundred or less are usually written out. Labor unions and other organizations often use figures.
  • Numbers of one million and above are easier to read if written as figures with the word “million,” “billion,” etc.
  • Written-out numbers between 21 and 99 are hyphenated.
  • Figures of four digits may be written with or without a comma.
  • Numbers of checks, contracts, military hours, pages, policies, rooms/suites, streets, telephone numbers, and years are written without commas.
  • Check, telephone, and serial numbers may contain hyphens.
  • A fraction used as a modifier is hyphenated, e.g., three-quarter time.
  • A fraction used with a whole number is written as a figure, e.g., 5 1/2, as are measurements that are fractions, e.g., “/10 mile.
  • A measurement as a modifier is hyphenated, e.g., nine-pound boy.
  • Numbers in a series or set are written alike, e.g., 50 to 60 participants.
  • Street names that are numbers are written out, but may also be written as figures from 13 and over.
  • Document divisions are usually written as figures, e.g., Psalm 100, page 7.
  • Ordinal numbers are not used in full dates; commas are not used in between just a month and year.
  • Money designations of one or two words are often written out, e.g., one dollar.
  • Times are usually spelled out in text and may be when used with “o’clock.” Figures are used for exact times, e.g., 8:13. Times may be used with “a.m./A.M.,” “p.m./P.M., “o’clock,” or “in the ~” but those designations should not be combined.
  • Year and page numbers may omit hundreds and replace with a dash, e.g., 1989-90,” “pp 140-50.
  • If an abbreviation or symbol is used with a number, it should be written as a figure.
  • Numbers should not be divided at the end of lines.
  • Plurals of written-out numbers are formed by adding s or es.
  • Plurals of figures are formed by adding s or ‘s.

Parentheses ( )

  • Used to enclose supplementary matter that is not intended to be part of the statement.
  • Appear in numeric data, including Arabic numerals confirming a spelled-out number, and in other mathematical expressions.
  • Set off explanations, definitions, translations, alternatives.
  • Enclose the abbreviation of the spelled-out word or the spelled-out form of an abbreviation.
  • Used in bibliographical data, cross-references, and comments about the text.
  • May appear in numbers or letters indicating an item in a series are enclosed such as: (1), (2), (3) and (a), (b), (c).
  • At the end of a sentence, the period follows the closing parenthesis.
  • A complete sentence within parentheses has its own punctuation.

Period (.)

  • Used at the end of a declarative sentence and after a question that is a suggestion and which does not require an answer.
  • Used after a letter or number indicating an item in a series.
  • Used as part of an ellipsis.
  • Appears in numbers with integers and decimals.
  • Used in some abbreviations.
  • Used after a person’s initials.
  • Centered, to indicate multiplication, i.e., 2·3=6.


  • The possessive case of most nouns is formed by adding an apostrophe or an apostrophe and s.
  • Possessives for singular and plurals nouns not ending in an s or z sound are formed by adding ‘s.
  • Possessives of singular nouns ending in an ‘s or z sound are usually formed by adding‘s, though some writers may prefer just an apostrophe. An exception is for multi-syllabic words if they are followed by a word beginning with an s or z sound.
  • Possessives of plural nouns ending in an s or z sound are formed by adding only an apostrophe. An exception is for one-syllable irregular plurals: add s.
  • In a phrase, individual possession is shown with a ‘s added to each noun, e.g., Barbara’s and Kyle’s bicycles; joint possession is shown by adding an apostrophe or to the last noun in the series or by adding an apostrophe or s to each noun, e.g., Barbara and Paul’s house.

Question mark (?)

  • Used for punctuation after a direct interrogatory statement and one expressing doubt.
  • Used after each element of an interrogative series when the series is not enumerated or lettered.
  • Do not put a comma after a question mark that falls within quotation marks.

Quotation marks (” “)

  • Quotation marks are used for direct quotations. Each part of an interrupted quotation begins and ends with quotation marks, as “I am getting worried,” she said, “that he has not called.”
  • Used for expressions following introductory terms such as: entitled, the word, the term, marked, designated, classified, named, endorsed, cited as, referred to as, signed, all of which indicate a borrowing or special use.
  • Placed around words referred to as words, such as: I said “tomato,” not “potato.”; and around sentences referred to as sentences, as in: An example of a question is, “Where the heck are they?”
  • Quotations may be used around mottos, slang, misnomers, coined words, proverbs and maxims, ironical reference, and unspoken dialogue.
  • Used for translations of foreign terms.
  • Used for single letters within a sentence, e.g., His name begins with a “K.”
  • Sometimes used to enclose document titles and parts, and addresses within a sentence, e.g.: Her book, “14,000 Things to be Happy About,” is a best seller.
  • In American usage, punctuation that goes inside the closing quotation mark includes a period or comma (but not a colon or semicolon). In British usage, the period and the comma go outside the quotation mark. The dash, question mark, and exclamation point fall inside quotation marks if they belong with the quoted matter but outside if they punctuate the sentence as a whole.
  • For quotations which extend beyond one paragraph, a quotation mark begins each paragraph and the closing quotation mark is at the end of the last paragraph.
  • Some writers now leave a preceding comma out before a quotation.
  • Some writers leave periods and commas outside of quoted material if that punctuation belongs to the sentence as a whole.

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Semicolon (;)

  • This punctuation sometimes is regarded as a weak period or strong comma, and is used in ways similar to periods and commas.
  • A semicolon can mark the end of a clause and indicate that a clause following is closely related to it.
  • A semicolon can also divide a sentence to make meaning clearer. A semicolon is placed outside quotation marks and parentheses.
  • Separates independent clauses in place of a coordinating conjunction or ellipsis.
  • Separates independent clauses when the second begins with a conjunctive adverb as in: accordingly, all the same, also, as a result, besides, by the same token, consequently, furthermore, hence, however, indeed, in that case, likewise, moreover, nevertheless, on the other hand, otherwise, still, then, therefore, and thus. These usually explain or summarize preceding matter.
  • Clarifies meaning in long sentences and in those with several commas. The indication of a strong pause by the semicolon helps the reader understand the meaning.
  • May be used before explanation phrases and clauses such as: for example, for instance, i.e., namely, that is.
  • Separates lists or phrases in a series when the phrases themselves have commas.

Single quotation marks (‘ ‘)

  • Single quotation marks are used to enclose a quotation within a quotation.
  • May be used around words that are special terms or for words referred to as words.

Slash (/)

  • The slash is punctuation also called the virgule, diagonal, solidus, oblique, or slant.
  • It is mainly used to show that a word is not written out.
  • A slash represents ‘or’ or ‘and/or’ in alternatives such as: yours/mine.
  • A slash may represent ‘and’, as in: 1990/91, Minneapolis/St. Paul.
  • A slash may represent some prepositions, such as: at, for, versus, with, i.e., c/o addressee, w/dressing.
  • A slash represents ‘per’ or ‘to’ in measures and ratios, as in: 2 ft./min., price/earnings ratio.
  • A slash is used to separate numbers in dates, fractions, and telephone numbers.
  • A slash may be used to separate parts of an address or divide lines of poetry when written as continuous text.
  • A slash is used in pronunciations (phonemic transcriptions).

Common errors in punctuation:

  • Using the apostrophe for plurals: “plural’s” is incorrect, “plurals” is correct.
  • Using the punctuation mark inside the quotation mark: correct for American usage; punctuation marks go outside the quotation marks in British English.
  • Using punctuation in parentheses: the punctuation goes inside the parentheses if what is within the parentheses constitutes a complete sentence.

For deeper exploration of these punctuation marks, see our other posts:

Apostrophe (‘)
Comma (,)
Em dash
Hyphen (-)
Semicolon (;)
Slash (/)