Get your punctuation right

This is not a definitive or comprehensive set of rules on punctuation, but a general guide as to how punctuation marks should be used. Please remember that experts often disagree on matters of punctuation and also that some punctuation rules go in and out of fashion over time. It is important to be consistent throughout the document and to ask if a house style is required by whoever will read the document. Punctuation style is sometimes a matter of personal preference, but consistency is paramount. 

1.The full stop(sometimes called the full point)    . 

The full stop is used to mark the end of a sentence. A sentence is a sequence of words which ‘make sense’, or to put it in a more formal way  —  a sentence must have a verb which agrees with its subject (in grammar, it is called a finite verb). 

Examples of sentences: 

Marygoesto town every day.   (‘Mary’ is the subject, ‘goes’ is the finite verb.) 

On the first Tuesday of the month which is market day in the town and when the streets are very crowded and the stalls are selling their goods, somepeople arrivein town early to avoid the crowds.

(‘people’ is the subject, ‘arrive’ is the finite verb.) 

Example of a sequence of words which do not form a sentence: 

When the weather is cold and the wind is blowing and it is snowing and it is dark outside 

This is not a sentence because it does not make sense on its own (and contains no finite verb). The reader may say ‘so what?’  and expect something else to be said. This could be made into a sentence by saying: When the weather is cold and the wind is blowing and it is snowing and it is dark outside, I stayat home.(‘I’ is the subject and ‘stay’ is the finite verb). 

Another use of the full stop is to mark abbreviations (words expressed in a shortened form) 

Examples: A.W. Jones(could be a shortened form of (A)rthur (W)illiam Jones

                 N. Wales(shortened form of North Wales) 

In some cases, a full stop is now not used, although it was in the past.

Examples: St Mary’s Church, Mrs Jane Smith. 

In abbreviations such as the UK (U.K.) or the USA, (U.S.A.) it is now more common not to use a full stop, but sometimes full stops are used. Also, it is now unusual to have full stops in abbreviations such as MA, PhD, BBC. One again, consistency is essential. 

Another form of abbreviation is the acronym.

Examples:  UNESCO (United Nations Educational and Cultural Organization)

                     OUP (Oxford University Press)

Full stops are not used with acronyms.  

2. The comma   , 

The comma is used to divide sentences or to separate words, phrases or clauses within a sentence.  

Examples:

Mrs Jones, who usually goes shopping every Friday, decided to go on Saturday this week.(In this sentence the clause ‘who usually goes shopping every Friday’ is separated from the main sentence by the commas. It could have been in brackets. In this case it is accepted to spilt the subject (Mrs Jones) from the main verb (decided). However, brackets are now less usual. 

However, the town was very busy on Saturday. 

Examples where if a comma is not included, the meaning is changed:

The cover of the book is red and blue is the colour of the magazine cover. 

This should be:

The cover of the book is red, and blue is the colour of the magazine cover. 

Other examples of the incorrect use of commas:

The car, which passed my house yesterday was travelling too fast. 

This should be:

The car which passed my house yesterday was travelling too fast. 

Commas should not be used to separate subject and verb or verb and object, except where the commas define a clause within the sentence (see above).

Examples: The house, was built in 1930. This is incorrect

               It should be: The house was built in 1930. 

            The athlete ran, quickly to the finishing line. This is incorrect

            It should be: The athlete ran quickly to the finishing line. 

Another use of commas is to separate items in a list (see ‘colon’ below). 

There are different opinions among grammar experts about the use of commas, but a good way is to read the sentence as though you are reading it to another person and where you would naturally pause is where you should usually place a comma. 

3. Brackets  

There are three types of bracket: parentheses ( ), square brackets [ ], and braces { }. Braces are usually used only in mathematics and science. Brackets are used to add some information which is not technically part of the text. Brackets are also used for in-text references.  

Examples: Isaac Newton (1643-1727) discovered gravity.

Oxford University (which claims to be the oldest university in the English-speaking world) sets very high admission requirements. 

In the latter example, it is now becoming more usual to use commas rather than brackets.

Oxford University, which claims to be the oldest university in the English-speaking world, sets very high admission requirements. 

Square brackets are generally used to give in-text explanations.

Example: Alaska is the most westerly state of the USA [It previously belonged to Russia].                

4. The semi-colon   ;

The semi-colon is used to divide long sentences into what are called clauses and even to divide complex sentences into multiple sentences. A semi-colon is a ‘stronger’ break than a comma, but not as strong as a full stop. It helps to make complex sentences easier to read and understand. 

Example:

The university has grown in recent years and now has over 12,000 students studying a number of different subjects, but has a strong bias towards science; this is good for the economy of the city. 

Although a full stop could be used after ‘science’, the sentence which follows it is very short and it is better to use a semi-colon as the short ‘sentence’ is of the same subject as the main sentence.  

5. The colon     :

The colon leads forward and usually introduces a list, or a conclusion. 

Examples:

(a)   The following subjects are taught at the university: biology, chemistry, mathematics, physics, and computer studies. 

OR

(b)   The following subjects are taught at the university: biology, chemistry, mathematics, physics and computer studies. 

Where there is a list as in the first example above, there are two opinions as to whether a comma should be used after ‘physics’ and before ‘and computer studies’. In this case, the comma is known as the serial comma (or the Oxford comma because it is required in the house style of the Oxford University Press). Example (a) uses the Oxford comma, but (b) does not. It is wise for writers to check with publishing house or academic institution as to their house style as this matter is somewhat controversial.                   

6. The apostrophe     ‘           

The apostrophe is the most misused of all the punctuation marks.  

It is used denote possession (belonging)

Examples:

Mary’s book. (The book which belongs to Mary)

The car’s engine (The engine of the car)

The dog’s lead   (The lead of the dog) 

In plural nouns ending in ‘s’, the apostrophe is placed after the ‘s’ 

Examples:

The students’ books (The books belonging to all of the students _ plural)

but note:

The student’s books (The books belonging to one student _ singular) 

In two-months’ time 

When the plural does not end in ‘s’, the apostrophe is placed before the ‘s’ (Note the hyphen) 

Example: The people’s favourite shop 

Common mistakes involving the apostrophe:

Potato’s on special offer today

Should be: Potatoes on special offer today 

There are no trains here on Sunday’s.

Should be: There are no trains here on Sundays. 

(a)  To denote a shortened form of words: 

Example:  It’s  (it is);  you’re (you are);   don’t(do not)  

Common mistakes:

This is you’re car.  Should be This is your car.

Its very busy here today.  Should be: It’s very busy here today. (It'sin this sentence means it is) 

Note: The shortened form of words (it’s, don’t, can’t) should not normally be used in academic writing, but only in informal writing and in speech. 

7. The question mark     ?

The question mark is placed at the end of a question and replaces the full stop. 

Example:  Where are you going? 

Incorrect use of question mark:

It should be asked if the experiment was successful?

This sentence should end in a full stop and not a question mark. 

8. The exclamation mark    ! 

The exclamation mark expresses surprise or astonishment. It replaces the full stop. 

Examples:  We had a heat wave in January!

                 Don’t pour water over your computer!

                 Wow!   (This word should not be used in academic writing)

Do not overuse the exclamation mark. It can lose its impact and it is the equivalent of shouting too much.  

9. Quotation marks (also called inverted commas)    “ “   ‘ ‘ 

Quotation marks are used to quote words said by another person. These are often used in academic writing to refer to the actual words from some literature. 

Example:

Professor Smith said, ‘This experiment would have been more successful if there had been more participants’. 

Quotation marks should not be used if the text is not a direct quotation. 

Example:

My neighbour said that the wind had blown her garden shed down.

or if quotation marks are used this should be:

My neighbour said: ‘The wind has blown my garden shed down.’ 

Single ( ‘ ‘) or double (“ “)  quotation marks ? 

This is much debate about this among grammar experts. The usual current practice is to use single quotation marks and only use double quotation marks for a quotation within a quotation.  

Example: The professor asked the student, ‘What do you mean by saying, “ I don’t understand your explanation?” ‘ 

The important point here is to be consistent. Use either single or double throughout the document. This is a matter of the house style of the publishing house or the academic institution. 

It is usual not to edit or paraphrase direct quotations out of respect for the person who is quoted. If quoted text is paraphrased, it could lead to a copyright issue. 

11. The hyphen    - 

The hyphen is used to join two (or sometimes three) words when they act as one, usually as an adjective. 

Examples: The university is a highly-rated establishment.

                but note: The university is highly rated. (no hyphen) 

                I like to have an up-to-date text book.

                  but note: I like to keep my research up to date.  (no hyphen) 

12. Dashes   –  — 

There are two types of dash, the en rule (a shorter dash – ) and the em rule (a longer dash —) . However, the difference between these usually applies only to professional printing houses and for most general purposes the difference can be ignored.    

The dash is used to show the relationship between two words. 

Examples: There is a good student–teacher relationship at the university.

                The London–Paris flights have been suspended today. 

                I crossed the channel today—a very rough crossing it was.  (longer dash) 

Sometimes the hyphen (see above) is used instead of the dash.

For the use of dashes, it is import to be consistent. 

13. Ellipses

Ellipses indicate that some words of a sentence have been omitted. They are usually in the form of three dots at the point where the words have been omitted. Ellipses are often used in direct quotations. Sometimes ellipses have a space between the dots (. . .) as in example (a) but sometimes they do not (…) as in example (b).

It is more usual today for there not to spaces between the dots, but some house styles require spaces.  

Example (a) The researcher said ‘There are many reasons why students find this subject difficult . . . but this makes them work harder.’ 

OR 

Example: (b) The researcher said ‘There are many reasons why students find this subject difficult … but this makes them work harder.’ 

14. Italics 

Although italics are not strictly punctuation, italicised text is increasingly used for names of publications, names of houses, names of ships etc. where quotation marks were previously used, although some writers may still use quotation marks. 

Examples:

(a)  I visit the library every morning to read The Times.

(b)  We named our houseSnowdoniabecause that is where we had our honeymoon.

(c)TheQueen Mary 2crosses the Atlantic from Southampton to New York. 

In example (b) above, it may still be common to use quotation marks instead of italics.

Either italics or quotation marks should be used but not both. It would be incorrect to say: I have ‘The Times’ delivered to my home every day. Use of italics or quotation marks is a matter of house style, but consistency is essential. 

15. Double-spacing between sentences 

Although this is a formatting issue rather than a punctuation one, it is useful to mention it here. In the days of manual typesetting, it was common practice to have a double space between sentences. (Example: The university term begins on 1 October.[double space]  First-year students are asked to register seven days before.)

In today’s world of electronic printing, this practice is generally considered to be outdated and has effectively disappeared and single space is used. However, some academic institutions or publishing houses may still require this.