When a sentence ends with an abbreviation, one period is used for the abbreviation and to end the sentence. 

1. Incorrect: In 1955, Richard and Maurice McDonald opened McDonald's Corp.. 

Correct: In 1955, Richard and Maurice McDonald opened McDonald's Corp.

One period indicates that "Corp." is an abbreviation and ends the sentence. 

Indirect questions end with periods, not question marks. 

1. Incorrect: The scientist wondered when will the sun explode? 

Correct: The scientist wondered when will the sun explode. 

This sentence is an indirect question therefore the sentence should end with a period.

When a sentence ends with parenthesis in which the parenthesis is part of the whole sentence, the period is placed outside the parenthesis.

1. Incorrect: Most mammals are omnivores (meaning they consume plant and animal matter.)

Correct: Most mammals are omnivores (meaning they consume plant and animal matter). 

The parenthesis portion of the sentence is part of the whole sentence, therefore the period is placed after the end parenthesis. 

Only an exclamation point is needed to express an exclamatory question. 

1. Incorrect: How on earth did this happen?!

Correct: How on earth did this happen!

Only an exclamation point is needed to express that this sentence is an exclamatory question.

When an exclamation point is used at the end of a quote, there is no need for a comma inside the closing quotation mark. 

1. Incorrect: "Be quiet!," the teacher yelled. 

Correct: "Be quiet!" the teacher yelled. 

The exclamation point ends the sentence inside the quotation marks. 

Question marks are used to end direct questions. Indirect questions do not end with a question mark, they end with a period. 

1. Incorrect: Can companies use solar power to operate factories. 

Correct: Can companies use solar power to operate factories?

This sentence is a direct question, therefore must end with a question mark. 

1. Incorrect: Does BCI technology improve lives?, is a question that requires further researched. 

Correct: Does BCI technology improve lives? is a question that requires further researched. 

The question mark takes the place of a comma in this kind of sentence.

Definitions and examples adapted from: https://www.thepunctuationguide.com

Commas are the most difficult type of punctuation to master. Commas can be used in almost all situations. There are many basic and complicated uses for commas.

If a degree or certification if shown after a person's name, the degree or certification should be separated from the sentence with commas. Common examples of degrees/certifications are PhD, Esq., MD, FACS...

1. Incorrect: Johnathan Walsh MD, FACS, concluded that lithium-ion batteries generated power at a faster rate than gas engines. 

Correct: Johnathan Walsh, MD, FACS, concluded that lithium-ion batteries generated power at a faster rate than gas engines. 

Commas should surround a persons name if they are being directly addressed.

1. Incorrect: Thank you Jonathan for your support on the project.

Correct: Thank you, Jonathan, for your support on the project.

This use of commas is typically obsolete in formal writing, but still important to know.

"When a date consists of the day of the month followed by the year, the day of the month should be followed by a comma. When the day of the week is provided before the month, the day of the week should be followed by a comma" (Jordan np).

1. [Month] [Number], [Year]

   • July 16, 2004

2. [Day of the week], [Month] [Number], [Year]

   • Saturday, July 16, 2004 

When a date is in the middle of a sentence, commas should appear both before and after the year. 

1. Incorrect: The study was concluded on Friday July 16 2004 after six years of testing. 

Correct: The study was concluded on Friday, July 16, 2004, after six years of testing. 

When a date is used as an adjective, reword the sentence. This is because comma rules surrounding this situation vary. 

1. Uncertain: The March 4, 2017, testing date was postponed to a later date.

2. Correct: The testing date scheduled for March 4, 2017, was postponed to a later date.

No comma should be included between the month and the year if those are the only two elements of a date present in a sentence.

1. Incorrect: The study was concluded in March, 2018. 

Correct: The study was concluded in March 2018. 

Note: Formal writing often utilizes the British style of writing dates which reduces the need for a comma. [Number] [Month] [Year]

Commas must be used to separate geographical elements. A comma should be placed after the final geographical element when said element is in the middle of a sentence. 

1. Incorrect: The test vehicle was driven from San Jose California to Rochester New York. 

Correct: The test vehicle was driven from San Jose, California, to Rochester, New York.

A comma should be used to separate a series of words, phrases, or independent clauses. Do not place a comma after the last item in a list unless the sentence structure requires it.

1. Lithium, cobalt, and nickel are the three fundamental elements to lithium-ion batteries. 

2. With efficiency of production, safety of the product, and practicality all in mind, Dr. Hobart started his research immediately.

The final comma in a list placed before the word "and" is known as a serial or oxford comma. Although some authorities do not require it, include this last comma to ensure clarity. 

A comma is needed when a noun is modified by multiple adjectives. 

1. The test method was a long, noisy process.

In these cases, a comma can sometimes replace the conjunction "and." 

Commas are used to separate nonessential information, nonessential explications, and interrupting elements from the rest of a sentence.

1. John articulated the study's results to his brother, Gregory.

A comma is needed only if the brothers name is grammatically nonessential (i.e. John only has one brother).

2. Dr. Spork,  an editor for the New York Times, recently addressed his critics. 

3. The work of the study was, frankly, inaccurate. 

This use is typically obsolete in formal writing as interrupting elements are often considered informal.  

The word "that" is a restrictive pronoun and phrases that include the word "that" do not need to be surrounded by commas. The word "which" acts as a nonrestrictive pronoun and phrases that include the word "which" need to be surrounded by commas. 

1. The electric batteries that were created in Tesla factories are not currently consumer safe.

2. The electric batteries, which were created in Tesla factories, are not currently consumer safe.    

When an introductory word or phrase starts a sentence, a comma should separate said word or phrase from the main clause of the sentence.

1. However, the data collected from Jonathan's study was manipulated greatly.  

2. First of all, the article did not properly cite the material being referenced. 

When a word or phrase follows the main clause of a sentence, and is at the end of a sentence, said word or phrase should be preceded by a comma. 

1. The study did not provide conclusive results, however.

Commas are necessary in compound sentences when the two independent clauses are joined by a coordinating conjunction/FANBOY. (FANBOYS: for, and, nor, but, or, yet, so) 

1. The testing was completed, but the results had yet to be analyzed. 

2. There was a massive error in the sampling of participants, so the study needed to be reconducted.

When a nonessential comment is added before the second clause, sometimes previous rules can be ignored to avoid a sentence with too many commas. 

1. Incorrect: Dr. Scott originally pursued a career in chemistry, but, in the end, he decided to become a statistical analyst.

Correct: Dr. Scott originally pursued a career in chemistry; in the end, he decided to become a statistical analyst.

Because of the structure of the sentence, the word "but" needs to be removed in order to ensure clarity, readability, and grammatical correctness. 

Commas are typically not necessary in simple sentences. Simple sentences are sentences with only one independent clause and no dependent clause. Do not use a comma before a coordinating conjunction in a simple sentence.

1. Incorrect: The product was purchased, but not the extended warranty. 

Correct: The product was purchased but not the extended warranty. 

A comma should be included if the sentence lacks clarity or is more confusing without one.

1. The batteries were far more efficient this year than last, and far more efficient than expected. 

If the dependent clause comes before the independent clause, a comma is needed to separate the two clauses. This happens in complex sentence. A complex sentence is a sentence that "contains an independent clause and one or more dependent clauses" (Jordan np). The words that typically introduce dependent clauses in these situations are: if, because, while, as, although, since, and unless.

1. Because of the severe weather, testing had to be delayed. 

2. Because of the severe weather and lack of supplies, testing had to be delayed. 

If a sentence begins with two dependent clauses that both modify the independent clause, only one comma is needed.

If an independent clause precedes the dependent clause, a comma is not needed.

1. Incorrect: Testing had to be delayed, because of the severe weather.

Correct: Testing had to be delayed because of the severe weather.

This is true unless the dependent clause in nonessential to the meaning of the sentence, then a comma is required.

If the dependent clause is in the middle of the sentence use commas if the clause is nonessentials and omit commas if the clauses is essential (see previous examples on essential vs. nonessential clauses). 

A compound-complex sentence contains a dependent clause and two or more independent clauses. If the sentence begins with the dependent clause insert a comma after the dependent clause. Do not insert a comma in-between the independent clauses in this situation. 

1. Incorrect: If the proposal was to succeed, Dr. Lang needed to receive sufficient funding, and needed to discover a suitable location to test his product. 

Correct: If the proposal was to succeed, Dr. Lang needed to receive sufficient funding and needed to discover a suitable location to test his product. 

If the dependent clause occurs between the two independent clauses but only applies to the second, the dependent clause should be surrounded by commas.

1. Incorrect: The bill was rushed and unconstitutional and when they read the bill the opposing political party immediately attempted to have the bill discarded.  

Correct: The bill was rushed and unconstitutional, and when they read the bill, the opposing political party immediately attempted to have the bill discarded. 

The most common use of a semi-colon is to join two independent clauses when a coordinating conjunction / FANBOY is not used. (FANBOYS: for, and, nor, but, or, yet, so) 

1. 1. Incorrect: Self-driving vehicles are only legal on paved roads; but non-electric vehicles are legal on all roads.  

Incorrect: Self-driving vehicles are only legal on paved roads, non-electric vehicles are legal on all roads.  

Correct: Self-driving vehicles are only legal on paved roads; non-electric vehicles are legal on all roads.

1. 2. Incorrect: The data showed a strong correlation between battery size and carbon emissions; however, many other factors are still in play.

Correct: The data showed a strong correlation between battery size and carbon emissions; however, the data does not take into account other factors that contribute to carbon emissions.

Both the clause before and after the semi-colon must be independent (i.e. able to act as a standalone sentence).

Semi-Colons are also used between independent clauses which are connected by a transitional expression. 

1. Incorrect: Gas prices are very difficult to keep track of, a gallon of gas might cost $4.00 in the morning and $5.00 in the afternoon.

Correct: Gas prices are very difficult to keep track of; thus, a gallon of gas might cost $4.00 in the morning and $5.00 in the afternoon.

The transitional expression (thus) makes the sentence require a semi-colon. 

Note: Because semicolons can be substituted with colons, periods, and certain comma structures, the best way to use a semi-colon correctly in formal writing is to avoid using one.  

A colon is primarily used to introduce a list.

1. 1. Incorrect: Batteries are made primarily of three materials lithium, cobalt, and nickel. 

Correct: Batteries are made primarily of three materials: lithium, cobalt, and nickel. 

1. 2. Incorrect: Dr. Robert specializes in: organic chemistry, molecular biology, and technical writing.

Correct: Dr. Robert specializes in organic chemistry, molecular biology, and technical writing.

A colon should NOT be used when listed items are incorporated into the structure of a sentence. 

A colon can also be used between independent clauses when the second explains the first. 

1. Incorrect:  A specific major concentration is still important when searching for jobs according to a recent study which revealed that job applicants with a major concentration were hired 61% more often than applicants without one. 

Correct: A specific major concentration is still important when searching for jobs: a recent study revealed that job applicants with a major concentration were hired 61% more often than applicants without one. 

In this instance, a colon improve clarity and reduce the wordiness of the sentence.

A colon can be used in place of an em dash to add emphasis. 

1. Incorrect: After weeks of discussion and deliberation: a final decision was made, guilty.

Correct: After weeks of discussion and deliberation, a final decision was made: guilty.

Correct: After weeks of discussion and deliberation, a final decision was made—guilty.

There are also many non-grammatical uses of colons.

1. Time: The experiment started at 11:00 A.M.

2. Ratios: The experiment showed the the ratio of products to reactants was 6:1. 

3. References: This is similar to the passage written in John 1:2. 

Note: Similarly to semi-colons, only use colons when absolutely necessary to ensure the message of a sentence is as intended.  

Hyphens are used to join words or parts of words together. 

1. Incorrect: The use of low grade fuel damages vehicles with weak engines. 

Correct: The use of low-grade fuel damages vehicles with weak engines. 

Low-grade is a compound term and requires a hyphen in between the word "low" and "grade". 

Compound adjectives are hyphenated. A compound adjective is two or more words acting as one adjective. 

2. Incorrect: Grass fed cows are generally healthier than feed fed cows. 

Correct: Grass-fed cows are generally healthier than feed fed cows. 

Grass-fed is a compound adjective and acts as one adjective in the sentence.

En Dash (–)  

Used to show a span or range of numbers in certain cases.

1. Example: 2018–2020 showed the highest profit margins. 

2. Incorrect: Lithium was mined in excess from 1998-2004 before regulations were put in place. 

Correct: Lithium was mined in excess from 1998 to 2004 before regulations were put in place. 

An en dash should not be included in a sentence if the range is introduced with words like "from" or "between."

Em Dash (—) 

The em dash is one of the most versatile punctuation marks. The em dash can used as a substitution for commas, parentheses, or colons.

However, in formal writing, an em dash should typically only be used to indicate missing portions of a sentence. 

1. Due to a poor connection, John was only able to hear part of Alex's report: "The st——y demonstrated that a higher pr——t m—— were possible."

2. The lead research of the study was very critical of the article saying, "Dr. Ross is speaking total bulls——t, he has no authority to make such claims."

An em dash can be used when words are unknown or intentionally omitted. Two or three em dashes can be used to show a missing word, but the number should be consistent throughout the entire document. 

Note: Since hyphens, em dashes, and en dashes all look very similar and can serve a variety of purposes, avoid using these types of punctuation unless absolutely necessary.

Definitions and examples adapted from: https://www.thepunctuationguide.com

Apostrophes are used in contractions to show the omission of letters in a word. (don't= do not)

1. 1. • Note: avoid using any contractions in formal writing.

Apostrophes can be added to make a word plural but these cases are rare.  

1. Incorrect: Sadie got three Ds and a C this semester.

Correct: Sadie got three D’s and a C this semester.

1. Incorrect: Who’s case study is this?

Correct: Whose case study is this?

3. Incorrect: He stayed online for hours’ to research for his essay.

Correct: He stayed online for hours to research for his essay. 

To make a word possessive, add an (s) to the end of the word to show possession of the object.

1. Incorrect: Sadies essay 

Correct: Sadie's essay 

2. Incorrect: Sadie and Todds ice cream

Correct: Sadie and Todd’s ice cream

When a (s) already exists, writers add a (‘) on the outside of the (s) to show possession.

1. Incorrect: Two cat's toys   

Correct: Two cats' toy

You use quotation marks on both sides of a quoted material. You capitalize the first letter in the quote when the quoted material is a complete sentence.

1. Incorrect: Sadie claims, “football research Is extremely beneficial for athletes.”

Correct: Sadie claims, “Football research Is extremely beneficial for athletes.”

If the quotes only are a fragment of the author's works do not capitalize the first letter.

1. Incorrect: The study indicated that the player “Position had the most significant effect on head impact exposure in this study of collegiate. These differences across player position were considerably greater than the differences we previously reported among the teams and season in both frequency and severity of head impacts'' (Beckwith, 2011, 2676).

Correct: The study indicated that the player “position had the most significant effect on head impact exposure in this study of collegiate. These differences across player position were considerably greater than the differences we previously reported among the teams and season in both frequency and severity of head impacts'' (Beckwith, 2011, 2676).

When the quote is interrupted mid-sentence you do not capitalize the second part of the quotes. 

1. Incorrect: “Cats and dogs are the best animals,” Sadie said, “The genetic research behind the domestication is super interesting.”

Correct: “Cats and dogs are the best animals,” Sadie said, "the genetic research behind the domestication is super interesting."

With regards to punctuation at the end of the quote if the sentence ends after the quoted material from a source there will be no punctuation inside the “” but rather there will be a period after the ()

1. Incorrect: "The common age youths are starting to play football is too young which increases the risk for further damage." (Carron 467)

Correct: "The common age youths are starting to play football is too young which increases the risk for further damage" (Carron 467).

Punctuation at the end of the sentence will be inside the ("") when the author Is stated before the quoted material. 

1. Incorrect: Connor tells everyone, “Climate change needs to be discussed”.

Correct: Connor tells everyone, “Climate change needs to be discussed.”

When the sentence continues after the quote a comma will be inside the quote material to indicate a change to the author’s writing. 

1. Incorrect: “Coaching techniques may provide more benefit for reducing head injury metrics than exercise programs” as the program observed by doubling strength in the neck muscles concussive impact levels decreased by 2 percent (Merryweather 109411).

Correct: “Coaching techniques may provide more benefit for reducing head injury metrics than exercise programs,” as the program observed by doubling strength in the neck muscles concussive impact levels decreased by 2 percent (Merryweather 109411).

Ellipsis are useful in omitting words. This allows for only important information to be included in a document. 

• • Cal Poly was started in March in 1901 and has gone through various major renovations since its opening. The school has competitive admissions and provides students with challenging classes. 

1. Incorrect: Cal Poly has competitive admissions and provides students with challenging classes.  

Correct: Cal Poly ... has competitive admissions and provides students with challenging classes. 

• • “The authors believed that she got sick from the constant rain. She was in the hospital for weeks.”

2. Incorrect: “sick from the constant rain. She was in the hospital for weeks.”

Correct: “...sick from the constant rain. She was in the hospital for weeks.”

Ellipsis are also used to suggest the idea of more.

1. Incorrect: To be continued

Correct: To be continued...

Parentheses are used to further explain information. The author must write as if they are not included within the sentence since parentheses are not part of the subject.

1. Incorrect: Dr. Sadie Keen (and her researchers) were always welcome. 

Correct: Dr. Sadie Keen (and her researchers) was always welcome. 

To correctly cite an intext citation.

1. Incorrect: A valid study performed with Dr. McKee showed the true extent, “finding CTE in 99% of the NFL players studied, 91% of the college football players, and 21% of the high school players” Mez 369.

Correct: A valid study performed with Dr. McKee showed the true extent, “finding CTE in 99% of the NFL players studied, 91% of the college football players, and 21% of the high school players” (Mez 369).

Abbreviations and acronyms, writers usually include the full name and put the acronym in parentheses. 

1. Incorrect: The National Football League NFL is one of the most popular sports in American. 

Correct: The National Football League (NFL) is one of the most popular sports in American.

Lists that include number or lettered usage need to include parentheses surrounding the numbers or letters.

1. Incorrect: In this class you will use: 1 notebook, 2 loose leaf paper, and 3 a binder.

Correct:In this class you will use: (1) notebook, (2) loose leaf paper, and (3) a binder.

Brackets are used as clarification to allow for the addition of quoted material to read properly within the sentence was a whole. 

1. Incorrect: Football is "one of the most popular (American) sports

Correct: Football is "one of the most popular [American] sports

To indicate a change in capitalization 

1. Incorrect: "studies performed on athletes must be accurate in order to result In trustworthy data."

Correct: "[S]tudies performed on athletes must be accurate in order to result In trustworthy data.

To indicate an error within the text, which has been revised.

1. Incorrect: "Doctor MeKeen's research was able to prove (with 90 percent accuracy) athletes perform better with carbohydrates being Ingested within thirty minutes prior to work out."

Correct: "Doctor MeKeen's research was able to prove [with 90 percent accuracy] athletes perform better with carbohydrates being Ingested within thirty minutes prior to work out."