Writing well is an essential tool in many professional and personal aspects of our life. One of the basics of writing – that is, when to use a comma – is often a stumbling block of many. There are, however, some basic guidelines and rules of comma use. If followed, they can significantly improve one’s skills when using the comma. This, in turn, adds to the overall quality and readability of the writing. If a piece of writing is easily comprehended, it will less likely present ambiguous connotations. A stronger and more accurate message will be the result.
The University of New England (2008) explains the basics of when to use a comma using four fundamental guidelines. These relate to sentence introducers, sentence coordinators, sentence inserters, and linkers.
The comma is used after a sentence introduction if the sentence begins with an adverb or transition text. This separates the introducer from the main clause (University of New England, 2008). The introduction could be an adverb, such as 'recently', or a transition word, such as 'consequently'. Both require a comma after the text. A comma will also be necessary after a dependent clause starts the sentence.
Sentence coordinators are also another scenario for when to use a comma (University of New England, 2008). That is, a comma should be used when independent clauses are being compounded (see also Basics of Punctuation).
Another rule for comma use relates to sentence interrupters. Separate words that are not essential in a sentence by a pair of commas. For example, ‘The great writer, Mr X, travelled to France’. There is an exception to this rule. If the inserter is core to the meaning of the sentence, then you do not surround it with a pair of commas.
Commas are also used as linkers in lists (University of New England, 2008). When providing a list within the text, commas are used to separate the series.
As for the use of a comma to link items, when adding additional text to the end of a sentence, use a comma to link this extra information to the main part of the text.
Commas are also used to break up two or more coordinate adjectives that explain a noun (Purdue University, 2009). A coordinate adjective refers to an adjective that has equivalent importance in explaining the noun. Do not add a comma between the last adjective and the noun.
There is also no need to use a comma when the adjective is a non-coordinate (Purdue University, 2009). For example, coordinate adjectives are seen in the sentence: 'He was a fast, agile athlete'. An example of a non-coordinate, however, is: 'It was a blue fast car'.
These are the basic rules of when to use a comma. There are always exclusions to the rules; however, in many circumstances, these will provide a good foundation.
Don’t think of commas as an inconvenience. Instead, commas prevent ambiguity and reinforce meanings in the sentence. They act as signposts for the reader and ensure that the message is clearly communicated and understood.
References
Purdue University 2009, The Owl at Purdue: Extended Rules for Using Commas, viewed 9 July, 2009.
University of New England 2008, Punctuating with Commas, viewed 9 July, 2009 (pdf).