While there are no hard and fast rules about punctuation, there are good style guidelines. This is a list of our ten most commonly used punctuation marks and a guide to their use.
10. Comma
Use commas to separate independent clauses in a sentence, for example:
The game was over, but the crowd refused to leave.
[amazon asin=1592402038&template=*lrc ad (left)]Yesterday was her brother’s birthday, so she took him out to dinner.
Use commas after introductory words, phrases, or clauses that come before the main clause:
While I was eating, the cat scratched at the door.
If you are ill, you ought to see a doctor.
NOTE: You should not do the reverse of this. For example, the following two cases are wrong:
The cat scratched at the door, while I was eating.
You ought to see a doctor, if you are ill.
Introductory words that should be followed by a comma are: yes, however, and well. For example: Yes, you can come to the party[amazon asin=0316027901&template=*lrc ad (right)]
Use a pair of commas to separate an aside from the main body of the sentence. For example:
John and Inga, the couple from next door, are coming for dinner tonight.
You can test this by removing the aside from the sentence. If the sentence still reads correctly, you have probably used the commas as you should. In the case above, this would render: John and Inga are coming for dinner tonight.
Do not use commas to separate essential elements of the sentence. For example:
Students who cheat only harm themselves.
[amazon asin=158008740X&template=*lrc ad (left)]The baby wearing a yellow jumpsuit is my niece.
The Oxford Comma
I prefer the Oxford comma when dealing with lists. It is also known as the Serial Comma or the Harvard Comma. The Oxford comma is much more widespread in American English than British English. When using the Oxford comma, all items in a list of three or more items are separated. For example:
I love apples, pears, and oranges.
Note the comma after “pears”. Many people prefer not to use this style and will omit the final comma. We call this the Oxford comma because it is the standard method taught at Oxford University.
Use commas to set off all geographical names, items in dates (except the month and day), addresses (except the street number and name), and titles in names.
Birmingham, Alabama, gets its name from Birmingham, England.
July 22, 1959, was a momentous day in his life.[amazon asin=B00BTI6HBS&template=*lrc ad (right)]
Occasionally, you will see a comma between a house number and street. This is not wrong, it is just old fashioned. It is not done in modern times, however.
Use a comma to shift between the main discourse and a quotation.
John said without emotion, “I’ll see you tomorrow.”
“I was able,” she answered, “to complete the assignment.”
Use commas if they prevent confusion:
To George, Harrison had been a sort of idol.
9. Period or Full Stop
The primary use of a period is to end a sentence. Its second important use is for abbreviations. There are stylistic differences here. I will discuss both.
Fowler
Martin Fowler, author of Modern English Usage, says that we should place a period at the end of an abbreviation only when the final letter of the abbreviation is not the final letter of the expanded word. For example:
Jesus Christ was born c. 4-6AD
The abbreviation is for the word “circa” – as it ends in an ‘a’ and the abbreviation is normally ‘c’ – we include the period.
Mr Jones was happy to see his wife
St Patrick lived in Ireland
In the first case above, “Mr” is an abbreviation for mister. Because mister ends in an ‘r’ and the abbreviation includes that ‘r’, we omit the period.
Other
The other use of the period for abbreviations is to always include the period, regardless of whether the final letter is included.
Mr. Jones was happy to see his wife
If an abbreviated phrase is pronounced, we do not include periods. For example: NASA is correct, N.A.S.A is incorrect. In some cases the periods are omitted even when the word is not pronounced, usually because it is a very commonly known term. For example: UCLA (University of California, Los Angeles).
In the case of a word like et cetera (etc.,) we always include the period.
8. Question Mark
The question mark is a fairly easy punctuation mark to use. It has one use, and one use alone. It goes at the end of a sentence which is a question. For example:
How many will be at the party?
you do not include a period when using a question mark. You also do not use a combination of question marks and exclamation marks in formal writing, though this is gaining acceptance in informal writing – particularly on the internet.
One thing to be careful of is to not include a question mark when it is not needed:
WRONG: I wonder how many people will come to the party?
While you are expressing a thought that seems to require an answer, you are doing so with a statement. This is the most common mistake made when using a question mark.
