A comma is used to mark off certain ideas or elements within a sentence. When used correctly, commas give meaning to a sentence by separating and grouping phrases, words, and clauses. Commas mark a trivial break or a pause between different parts of a sentence, it marks off certain parts of a sentence.
There are numerous hackneyed examples of the havoc caused by a misplaced or omitted comma, and they have all come: Mr. G. W. E. Russell's story of the clergyman who would "wear no clothes, todistinguish me from my fellow-Christians"; the merchant who telegraphed "No, price too high," and found it read as "No price too high" ; the advertisment, "Wanted, occasionally respectable woman"; "This stone is erected to the memory of John Phillips, accidentally shot as a mark of affection by his brother"; "The witness said the judge was an unmitigated liar"; "He is, happily, married"; and such perversions as "Rose, a nurse of ninety years."
The Critical Comma
What is a Comma [,]? "A comma is a punctuation mark that separates words or phrases within a sentence"
Here is a list of some of the functions of a comma that every writer should know and follow:
The Independent & Dependent Clause
- Independent Clause
A group of words that contain both a subject and a predicate and can stand alone as a complete sentence. Commas are used before yet, nor, for, but, and, or, and so when they connect two independent parts. The second subject "I" starts the second independent part. E.g., "I would have gone to town with you, but I had to do some studying." Always make sure that the sentence is made up of two independent parts. The following sentence is made up of only one independent clause with one subject and two verbs and therefore does not need a comma. Oliver needed to go to the doctor but his car did not want to start. Missing subject.
- Dependent Clause
A dependent clause cannot stand alone as a whole sentence and when using it at the beginning of a sentence it is set apart from the rest of the sentence by using a comma.
- Commas are used after transitional words or phrases:(e.g., however, moreover, therefore, finally, by the way, on the other hand).
When it is used at the beginning of a sentence: "No, I cannot go." "Well, I think it is a good idea to go to church tomorrow." - Verbal and Prepositional Phrases: Commas are used after a phrase beginning with a particle, or an infinitive in a sentence and with a preposition: Understanding that she could not go, we did not invite her to the party. During the semester, we always have time to study towards the exam. To avoid being gated, the boy rather told the truth.
Use the Comma in a Series of Three
Items in a Series
Commas are used to separate three or more words or phrases in a series: I ate a hamburger, some chips, and an ice-cream at the bazaar.Direct Quotations
Use commas to set off a direct quotation in a sentence: "I always wanted to visit the USA," my daughter said.
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Commas in Direct Speech
- Everyday Material
The everyday material can be defined as professional titles, dates, locations and addresses. Each has its own rules with regard to where to place the comma in a sentence.
- Dates: She wrote her first test on April 25th, 2018.
- Address: We went to Wolsely, Cape Town last December.
The Parliament building is located in Parliament Street, Cape Town. - Professional Title: Dr Coetzer, PhD., teaches at the University of the Free State.
- Essential and Non-Essential Clauses
Non-essential clauses may be interesting to add, but the sentence will still be clear without it. Use commas around non-essential parts in a sentence. A clause may be non-essential or essential, depending upon its relationship to the meaning of the sentence. If an essential or non-essential clause is describing a noun or pronoun in a sentence, it is called an appositive clause.
Professor Joubert, the Head of Romance Languages, teaches French and Italian at the University. The Head of Romance Languages is non-essential and does not change the meaning of the sentence and is separated by commas. The woman who is the Director of the Writing Centre works late on Tuesdays. In this case: Who is the Director of the Writing Centre is an essential clause because it identifies the woman being referred to in the sentence and does not need commas around it.
https://carey.jhu.edu/uploads/files/Six_common_comma_usages.pdf
Where does the Comma go?
Some specimens that are sent in have an historical interest. An American Tariff Bill once printed an unintended comma in its free list, "fruit, trees, etc.," and over a million of dollars of revenue was lost before the mistake was corrected. Another well-known case is that of Lord George Sackville, who, while on trial was charged with contempt of court for making an ambiguous pause in saying, "I stand here as a prisoner unfortunately that gentleman sits there as my judge." It is also well known that, as the first line of the "Elegy," Gray originally wrote, "The curfew tolls, the knell of parting day," and decided that it was an improvement when the printer left out the comma.
The prize is divided between the senders of the following:
"There was an unfortunate error in the first report by Sir John French on the fighting in 1915. It appeared as follows:
'We captured the western outskirts of Hulluch, the village of Loos, and the mining works around it, and Hill 70.' But Hill 70' had not been taken, and the correct report omitted the last of the three commas."
From a daily paper a couple of years ago:
"Mr. MacDonald had to obey orders, which must have been distasteful to him as an Irish gentleman." (The comma should have been omitted).
From an issue of a Society paper:
"I hear that Lady M. paid her dressmaker the other day, a most unusual form of compliment."
NOTE In addresses, heading and endings to letters, punctuation is partly a matter of convention. The writer's address with the date in the right-hand corner is punctuated as follows:
(There is no comma after the street number;
Full stop at end of the address).
125 Jan Frederick Avenue,
Cape Town.
10th March, 2018.
Endings are punctuated as follows:-
With best wishes,
I am
Yours sincerely,
Alec MacGregor.
and
I am, Sir,
Yours faithfully,
Hannah Smith.
No comma is needed after '"am" unless the sentence is interrupted by some such word as "Sir." Although it may be argued that usage sanctions the comma after "am," it is more logical to omit it. The matter is, of course, quite unimportant.
The following marks belong to spelling rather than punctuation:-
The full-stop with abbreviations: The rule is: Put a full-stop when the letter of the abbreviation is not the last letter of the whole word, e.g., Appro. (for approval), Approx. (for approximately), but Mr and Mrs, because r and s are the last letters of Master and Mistress.
Source: EBH Joubert: English Grammar: Punctuations
https://carey.jhu.edu/uploads/files/Six_common_comma_usages.pdf
https://en.oxforddictionaries.com/punctuation/comma