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Grammar resource: Full stops and commas

“Writers sometimes think a comma goes where a speaker would pause. That is NOT a good rule of thumb.” [emphasis added]

Susan J. Behrens, Grammar: A Pocket Guide

Full stops

A full stop (or period) is primarily used to mark the end of a sentence. The main issue with them in academic writing is that many students do not use them enough. There is an assumption that long sentences are more academic. This is not true. Some academic concepts are difficult to describe in a simple sentence but the majority of sentences do not need to be complicated or overlong. See our page on Overlong sentences for guidance. See also Comma splices.

Full stops in abbreviations

A full stop is the standard punctuation to use after or between many abbreviated phrases and words. For example five p.m., Prof. Smith, Sgt. Jones, George W. Bush. However, the conventions are changing with many abbreviations no longer needing such punctuation. See our page on Abbreviations for more information on this.

Note that if a sentence ends with an abbreviation that normally has a full stop, you would only put one, never two together:

Example: 

The samples were taken at regular intervals finishing at 8 p.m.

In-text citations and full stops

If you are using Harvard or APA referencing styles and wish to include a citation at the end of a sentence, you should include it before the full stop:

Example: 

Groups of captive elephants show more variation than their wild counterparts (Schulte, 2000).

 

If using a footnote referencing style, including OSCOLA, the citation should come after the full stop:

Example: 

Proportional representation enables better representation of minority groups.2

 

Commas

Separating lists

In lists of three or more items, commas separate the elements.

Example: 

The elements of the nursing process are categorised as assessment, planning, implementation and evaluation. 

 

A note on the 'Oxford comma'

An Oxford comma precedes the 'and' before the last entry of a list. It is common in American English but is not used when writing in the UK. There is an exception - where the entries in a list may also contain the word 'and' and it clarifies which are the actual list entries.

 

Example: 

The colour options available are grey scale, black and white, and full colour.

 

In citation lists

Commas are used between the author surname and the date AND to separate citations from the same author. Semi-colons are used to separate citations from different authors:

Example: 

(Green, 2014, 2015; Jones, 2016; Smith & Penny, 2016) 

 

Separating supplementary elements in a sentence

Supplementary elements are those that can be removed without changing the overall meaning of the sentence. Commas are used at either side to to separate them from the main element:

Example: 

The research, which took place in America, suggested that age was a significant factor.

Edward VII, the eldest son of King George V and Queen Mary, was one of shortest-reigning monarchs in British history.  

Between adjectives

If you are including more than one adjective, separate them with a comma:

Example: 

The young, well dressed, well educated woman was clearly discriminated against.

Before co-ordinating conjunctions

If you are using conjunctions such as and, but, for, nor, yet, or, so to link two independent clauses (clauses that could grammatically stand alone as full sentences) you separate them by adding a comma before the conjunction:

Example: 

She had no reason to complain, but she decided to sue the authority.

The political landscape was changing, so it was decided to leave the decision until a later date.

 

An exception is the conjunction because. It is not usually necessary to precede it with a comma:

Example: 

Sir Thomas More was among many who suffered execution because he could not subscribe to the Act of Supremacy.

 

Unless it helps clarify the relationship between the clauses:

Example: 

I knew I would be able to retrain, because I had consulted the website and found an appropriate course.

It was not consulting the website that was necessary to get the knowledge - but finding the appropriate course.

To separate a dependent and independent clauses

This is only necessary when the dependent clause is used as an introduction as illustrated by the punctuation and text within these two sentences:

Example: 

If the subordinate clause comes first, a comma is needed to separate the clauses.

You do not need any additional punctuation if the main clause comes first.

 

Independent clauses start with subordinate conjunctions (although, where, despite, since, as a result etc.), or relative pronouns (which, that, whether etc.).  They can also start with verbs taking the -ing form:

Example: 

Having spent so much time learning to use SPSS, I was reluctant to change to another statistical package.

To separate introductory words or short phrases

There are many times when you use a single word or short phrase as an introduction to a sentence. These are followed by a comma:

Example: 

However, without further corroboration this is unconvincing.

Conversely, the cost of business rent rose in the northern counties.

On the other hand, the provision could be said to be more equal per capita.

 

Note that if these were in the middle of a sentence, they should be preceded with a semi colon:

Example: 

The argument was well made; however, without further corroboration it was unconvincing.

The cost of business rent fell in the southern counties; conversely, it rose in the north.

To separate direct speech or quoted elements from the rest of the sentence

Use commas between quoted elements or direct speech and the introductory or linking text:

Example: 

"I do not want to come with you," she said, "unless you promise to bring my dog too."

"Don't use so many bullet points in your presentations," said the tutor. "There is almost always a better alternative."

Corrigan (2016:63) asked, "to what extent do students feel part of your department or university?"

 

Notice that the in the middle example above, there is a full stop following the word 'tutor'.  If this were a comma, as in the previous example, it would be an example of a comma splice and would be grammatically incorrect. 

If the final example had been written in a different order, with the quote first, a comma would not be needed as the question mark takes its place (this is also true if the quote ends in an exclamation mark).

Example: 

"To what extent do students feel part of your department or university?" asked Carrigan (2016:63).