Importance of Punctuation Marks – A Guide for RDNs

Published on: 10/05/2023
Published By: Liz Jalkiewicz
Importance of Punctuation Marks

Let’s face it, we all probably need a mini refresher on the importance of punctuation marks and the writing rules that comprise the English language. Although we learned the basics in grade school, it’s easy to become comfortable in our writing style as time passes. So, I have created a three-part series: Essential Writing Guide for Dietitians, where I will cover the following basic writing rules: (1) understanding the importance of punctuation marks and their proper usage, (2) following basic spelling rules and avoiding common spelling errors, and (3) adhering to basic rules for proper English grammar.

To become better writers, we need to comprehend the significance of punctuation marks and their usage. There are 13 key punctuation marks in the English language that we should understand: period, question mark, exclamation point, comma, colon, semicolon, dash, hyphen, brackets, parentheses, apostrophe, ellipses, and quotation marks. As dietitian writers, learning the importance of punctuation marks will make the writing experience more manageable for both you and your reader.

If you’re unsure about how or where to use certain punctuation marks, question comma usage in your sentences, or second-guess the usage of quotation marks or the placement of apostrophes, then you’re in luck. In this series, we’ll break down the 13 key punctuation marks essential to writing good blog content, as well as other forms of writing, whether digital or print.

The Importance of Punctuation Marks

Using proper punctuation is essential for effective communication because it enables the reader to comprehend the message being conveyed clearly. In fact, without proper punctuation, the English language becomes almost incomprehensible. Incorrectly placed punctuation marks can entirely alter the intended meaning of a sentence, leading to confusion and misunderstanding.

The correct utilization of punctuation marks can accentuate emotions and thoughts within the text and provide the reader with the necessary pauses and breaks to fully absorb the content.

When reviewing a copy, one of the primary aspects that an editor or proofreader will examine is the appropriate usage of punctuation marks. So, ensuring the proper placement of punctuation marks can not only enhance the readability of your writing but also demonstrate your proficiency in the English language.

Let’s review the below 13 punctuation marks:

  1. The Period (.)
  2. The Question Mark (?)
  3. The Exclamation Point (!)
  4. The Comma (,)
  5. The Colon (:)
  6. The Semicolon (;)
  7. The Dashes
  8. The Hyphen ( – )
  9. The Brackets ( [ ] )
  10. The Parentheses ( )
  11. The Apostrophe ( ‘ )
  12. The Ellipses (…)
  13. The Quotation Marks (” “)

The Importance of Punctuation Marks

1. The Period (.)

Importance of Punctuation marks - The Period

The period is the most straightforward of all the punctuation marks. It denotes the end of a sentence. Easy, right?

Proper placement of the period with:


  • If the sentence ends with a parenthetical that’s part of the larger sentence, the period is placed outside the closing parenthesis.

Example: I’m going to the park today (if it doesn’t rain).

  • If the parenthetical itself is a complete sentence, the period goes inside the closing parenthesis.

Example: (I’m going to the beach this weekend.)

Quotation marks

  • If a sentence ends with quoted material, the period goes inside the quotation marks even if it’s not part of the original quote.

Example: The teacher said, “The test is tomorrow.”

  • However, if the quoted material ends with a question mark or exclamation point, the period is omitted.

Example: “I can’t believe we won!” the team cheered.

Abbreviations or titles

  • The general rule is to use a period with lowercase and mixed-case abbreviations (a.m., etc., Mrs., Mr.), but omit them with uppercase abbreviations (FBI, IRS, ATM).
  • However, many scientific and technical abbreviations are formed without periods, even though they are lowercase or mixed case (ie. kg – kilogram, Na – sodium, 1st -first).

Ok, this one drives me bananas. Do you place one or two spaces between sentences? The answer is simple: one space. When typewriters were commonplace, two spaces were used at the end of every sentence. As long as you are typing on a computer these days, single space between sentences is best practice.

2. The Question Mark (?)

Importance of Punctuation Marks - The Question Mark

A question mark also indicates the end of a sentence; however, it ends a sentence that is a direct question.

  • It’s used to show that a direct question has been asked, whether in direct speech or as part of the passage in writing.
  • When a direct question is asked within a larger sentence, it requires a question mark; and the comma that would normally be in its place is omitted. The exception to this is when the question mark is part of a title of work, then the comma is retained.

For sentences that utilize indirect questions, these would require a period.

3. The Exclamation Point (!)

Importance of Punctuation Marks - The Exclamation Point

The exclamation point is also used at the end of a sentence. Its primary purpose is to convey or express an intense emotion to the reader.

  • When a quotation ends with an exclamation point, omit the comma that would normally be placed inside the closing quotation mark.
  • If the exclamation point is part of a title of work or a proper noun, retain the comma.

To be effective, the exclamation point should be used in moderation. Of all the punctuation marks, this one is the most commonly overused in blog writing.

In lieu of the exclamation point, use more descriptive words to accurately express the emotion you hope to convey to your reader.

4. The Comma (,)

Importance of Punctuation Marks - The Comma

The comma is undoubtedly the most troublesome and misused punctuation mark of them all.

We use commas to insert a pause in a sentence and help break it up into manageable chunks.The reason for the pause can vary, such as to list ideas, phrases, or even alter the meaning or structure of a sentence.

Primary uses of commas:

  • Used in a direct address (John, it was so nice to see you!)
  • Indicates a pause in the sentence if spoken aloud
  • Separates grammatical components of a sentence
  • Breaks up two complete sentences
  • Separates items in a series or list in a sentence
  • Used for mechanical and stylistic reasons

Comma misuse results in comma splices, where two independent clauses are joined together with a comma instead of a conjunction.

The presence or absence of a comma can dramatically change the meaning of a sentence.

  • At times, inappropriate use of a comma can have it mean the exact opposite of what you intended.
The presence or absence of a comma can dramatically change the meaning of a sentence.
The importance of punctuations marks -Let’s eat kids! versus Let’s eat, kids!

The Great Debate: Oxford Comma

Commas in Numbers

  • CMS and Associated Press recommend using a comma in 4+ digit numbers.
  • Exclusions include years, page numbers and street addresses.

Commas in Degrees and Certifications

  • When degrees or certifications are shown after a person’s name, it should be set off with a comma.
  • When directly addressing someone, their name or title should be followed by a comma.


  • When a date consists of the day of the month followed by the year, then the day of the month should be followed by a comma.
  • And when the day of the week is provided before the month, the day of the week should be followed by a comma.
  • When only two elements of the date are used (month and year – October 2021), the comma is omitted.

Other mechanical or stylistic uses for commas

  • Commas separate geographic references.
  • Nonessential explanations should be set off with commas (ie . Jane, a staff writer at The New Yorker, …).
  • Introductory words or phrases as well as afterthoughts should usually include a comma. These are words or phrases that precede or follow the main clause at the end of a sentence.

Commas based on sentence structure

  • There are four main types of sentence structures:
    • Simple
    • Compound
    • Complex
    • Compound-complex

Simple sentences contains one independent clause and no dependent clauses.

  • A simple sentence can contain a conjunction, but the comma is not required.
  • However, if the lack of a comma leads to confusion, insert the comma.

Compound sentences contain two or more independent clauses linked by a coordinating conjunction.

  • Remember, independent clauses are those that can stand alone as complete sentences.
  • Most common coordinating conjunctions are and, but, and or.
  • Use a comma before a coordinating conjunction that joins two independent clauses.

Complex sentences include an independent clause and one or more dependent clauses.

  • A dependent clause cannot stand on its own as a complete sentence.
  • The conjunctions and prepositions used to introduce a dependent clause include if, because, while, as, although, since, and unless.
  • If the dependent clause comes before the independent clause, separate it with a comma.
    • When a sentence begins with two dependent clauses that both apply to the subsequent independent clause, insert only a single comma after the second dependent clause.
  • If the independent clause comes before the dependent clause, omit the comma. (Exception to the rule – if the dependent clause is not essential to the meaning of the sentence or it’s just additional information, then insert the comma.)

Compound-complex sentences contain two or more independent clauses and at least one dependent clause.

  • When a sentence begins with a dependent clause that applies to two independent clauses that follow, insert a comma after the dependent clause, but don’t insert the comma between the two independent clauses.

5. The Colon (:)

Importance of Punctuation Marks - The Colon

The colon has three primary grammatical uses and several non-grammatical uses.

  • Indicates that there is a list or a piece of information, such as a quote, an example, or an explanation
  • Links two independent clauses when the second clause explains, illustrates or completes the first
  • Emphasizes a single phrase or word at the end of a sentence (the em dash can be used for a similar purpose)

A colon also has non-grammatical uses for time, ratio, business correspondence and references.

6. The Semicolon (;)

Importance of Punctuation Marks - The Semicolon

The primary function of the semicolon is to create a series of ideas made up of several independent clauses as one single sentence.

The semicolon is commonly described as stronger than a comma, but weaker than a period.

Similar to a colon, the semicolon links two independent clauses, but these clauses are more closely related to each other than when you would utilize a colon.

It also helps eliminate a pause between two independent clauses (like a period would); and it’s used in place of a conjunction like but, yet, or, not, for, and so.

We also use the semicolon between two independent clauses linked by a transitional expression such as “accordingly,” “consequently,” “for example,” “nevertheless,” or “thus.”

Technically, we can replace the semicolon with a period because each independent clause is a complete sentence. However, the semicolon helps to emphasize the close connection between the two clauses.

Another use for the semicolon is within a list that uses commas.

7. The Dashes

Importance of Punctuation Marks - The En Dash
Importance of Punctuation Marks - The Em Dash

Dashes can be used in place of a comma, colon, or semicolon.

It’s typically used to tell the reader that a group of words has been added to a previous group as an afterthought. There are two types of dashes: the en dash and the em dash.

  • En dash
    • It’s used to denote a range between numbers, dates, times, or scores.
    • It’s slightly larger than the hyphen, but shorter than the em dash.

Do not leave a space between the en dash an its adjacent material

If you introduce a span or range with words like from or between, do not use the en dash; instead, write out from 2001 to 2010 (not from 2001-2010)

  • Em dash
    • Typically, the em dash is used in place of other punctuation marks – like commas, colons, or parentheses.
    • It’s used to indicate emphases, an interruption, or an immediate change of thought.
    • It can enhance readability or emphasize the end of a sentence.
    • The em dash is the most versatile punctuation mark.

8. The Hypen ( – )

Importance of Punctuation Marks - The Hyphen

The hypen looks similar to the dash, but in the printed form the hyphen is shorter than the dash.

The hyphen is used in compound words when two or more words are connected. It is not separated by spaces.

Do not use a hyphen in place of an en dash or em dash.

Compound words can be open (spaced), hyphenated, or closed (solid).

  • You can often find compound nouns or compound verbs in a good dictionary, on the other hand, compound adjectives will not be there.
  • Whether compound adjectives are hyphenated or not depends on their position in a sentence. For example, two or more words that collectively act as an adjective should be hyphenated when they appear immediately before the noun they modify.
  • The exception is when the compound adjective begins with an adverb ending in -ly (poorly produced movie). In this case the misreading is unlikely, so the hyphen is unnecessary.

*There is no clear rule or guideline to help us decide which words are hyphenated and which are not. Use your best judgement or consult with an expert.

9. The Brackets ([ ])

Importance of Punctuation Marks - The Brackets

These are used to clarify something in the sentence such as technical terms or explanations, a noun or pronoun, or to clarify a subject when quoting another person or text.

The brackets give additional information to the reader, but it’s not very closely related to the rest of the sentence. If you were to remove the brackets, the sentence would still make sense.

10. The Parentheses ( )

Importance of Punctuation Marks - The Parentheses

These are used by the writer to supply further details or additional information to the reader.

Parentheses can often be replaced with commas without changing the meaning of the sentence.

The parenthetical material does not have to be grammatically fundamental to the sentence (meaning the sentence can stand on its own without this information present).

  • When the parenthetical material is its own sentence, then the closing punctuation mark goes inside the closing parenthesis.
  • When the parenthetical materials is at the end of a larger sentence, then the closing punctuation mark goes outside of the closing parentheses.

Other special uses for parentheses include time zones, numbered or lettered lists, area codes, short translations, abbreviations or acronyms.

11. The Apostrophe (‘)

Importance of Punctuation Marks - The Apostrophe

There are 3 main uses for the apostrophe:

  • Contractions – indicate the omission of a letter in a word
  • Used to indicate possession
  • Used in the plural of lowercase letters
    • But not plural of symbols, capitalized letters, or numbers

Avoid the most common contraction-apostrophe error: the contraction of it is is it’s and the contraction of let us is let’s.

  • Without the apostrophe, its is the possessive form of us and lets is a form of the verb let, as in to allow or permit. 

When using an apostrophe to refer to years, it’s acceptable to only write the last two digits like ‘80s or ‘90s.

The apostrophe is seldom used to form a plural noun, but there are a few exceptions – abbreviations, letters and some words (ie. yes’s and no’s).

  • Possessive of a singular noun – the general rule is that the possessive of a singular noun is formed by adding an apostrophe and s, whether the singular noun ends in s or not.
  • Possessive of a plural noun – formed by adding only an apostrophe when the noun ends in s, and by adding both an apostrophe and s when it ends in any letter other than s.
  • Exception to the rule – only use an apostrophe for singular nouns that are in the form of a plural – or have a final word in the form of a plural – ending with an s.
  • A proper noun that is already in its possessive form is left as is.
  • Joint possession is indicated by a single apostrophe.
  • Individual possession are indicated by an apostrophe for each possessor.

12. The Ellipses (…)

Importance of Punctuation Marks - The Ellipses

An ellipsis is three periods used together to indicate an omission of letters or words.

We often use it to jump from one sentence or phrase to another while omitting unnecessary or obvious words. It’s most useful when working with quoted material.

Each period should have a single space on either side, except when adjacent to a quotation mark, in which case there should be no space.

In informal writing, we commonly use it to represent the trailing off of a thought.

Example: “I’m not sure what to say…I’m just really happy for you,” her mother said.

13. The Quotation Marks (“ ”)

Importance of Punctuation Marks - The Quotations Marks

We primarily use quotation marks to indicate reproduced material word for word.

  • Single quotation marks are most frequently used for quotes within quotes.
  • Double quotation marks are used to denote text, speech, or words spoken by someone else. It’s also used to indicate dialogue.

The comma is the most common way to introduce a quote.

  • Commas and periods that are part of the overall sentence go inside the quotation marks, even though they are not part of the original quote.
  • Unless they are part of the original quotation, all other marks, except for commas and periods, go outside the quotation marks.

Two main ways to quote the words of others:

  • Run-in quotations
  • Block quotations (typically used with longer quotations) and since this is set off by the main text, you do not need quotations here; just differentiate the text by making it a slightly different size font or reduced line spacing.
    • Longer quotations can be defined as 100 words or more by the Chicago Manual of Style.
  • The colon is the most commonly used way to introduce a block quotation or when the quoted material could stand as a sentence on its own.

Remember, that quotation marks are not proper substitutes for italics.

Other uses for quotation marks include writing about letters or words, translations, sneer quotes, or nicknames.

The Importance of Punctuation Marks: A Review

Using proper punctuation is essential to communicate your message clearly and effectively. By understanding the importance of punctuation marks and their proper usage, you can avoid any confusion and misunderstandings that may arise from incorrect usage.

I hope you found this post to be a valuable resource that you can refer to when you need a little refresher on the 13 common punctuation marks in the English language. Mastering the art of punctuation in your writing will not only enhance your communication skills but also make it easier for your readers to understand your message. So, keep practicing and don’t hesitate to revisit this guide whenever you need to brush up on your punctuation skills.

FREE Bonus Content

6 Common Punctuation Mark Mistakes to Avoid
6 Common Punctuation Mark Mistakes to Avoid

*Note: Article updated September 2023 by Danielle Mortell, student in the Fall 2023 cohort of The Dietitian Editor Volunteer Program and Mentorship.


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