This page offers an explanation on the correct use of commas and gives examples of commas used in sentences.
A comma is used:
A comma is used:
- After setting the scene at the start of a sentence (e.g., Now I'm older, I understand. )
- After transitional phrases like However, Consequently, or As a result (e.g., As a result, I now understand. )
- After an interjection (e.g., Jeepers, now I understand. )
- Before a conjunction joining two independent clauses (e.g., I like cake, and I like cheese. )
- As parentheses (e.g., Janet and John Baxter, who live next door, adore cakes. )
- To separate list items (e.g., bread, milk, and cheese () / bread, milk and cheese () – more on this below.)
- After a long subject if it helps the reader (e.g., A, B, C, and D, are required to bake this cake. )
- In numbers (e.g., 3,213 )
- With the vocative case (e.g., I know your auntie, John. )
- Before a quotation (e.g., She said, "I understand." )
Rules for Using CommasBelow are the rules for using commas.
Using Commas after "Setting the Scene"
It is quite common for a sentence to start with words which "set the scene." These words usually state a place, a time, a condition, or a fact before the main part of the sentence. Words that "set the scene" at the start of a sentence are usually followed by a comma. You do not have to use a comma; i.e., it's not a strict ruling. It's just a common style. However, as it will help your reader, it is a useful style to adopt. For example:
Using Commas after a Transitional Phrase
A transitional phrase is a term like However, Consequently, Therefore, and As a result. (There are others, but these are the most common.) A transitional phrase usually sits at the start of sentence and acts like a bridge to a recently mentioned idea (often an idea in the preceding sentence). A transitional phrase is usually followed by a comma. For example:
Read more about using a comma after a transitional phrase
Using Commas after an Interjection
An interjection is usually a short word inserted into a sentence to express an emotion or feeling. Expressions such as yes, phew, and indeed are examples of interjections. Often, an interjection will sit at the start of the sentence but not always. It is normal practice to offset an interjection with a comma (or commas if it's in the middle of the sentence). In the examples below, the interjections are shaded:
Read more about using a comma after an interjection
Using Commas before a Conjunction
Words like and, or, and but are known as conjunctions. (There are other conjunctions, but these three are the most common.)
When a conjunction joins two standalone sentences (or independent clauses), it is usual to place a comma before it. For example (conjunctions shaded):
Read about the Oxford Comma
Using Commas for Parentheses
We all know that additional information (such as an explanation or an afterthought) can be offset with brackets. However, brackets are just one of the choices you have. You can also use commas or dashes. The information which is offset by commas, brackets, or dashes is called a parenthesis. The punctuation marks used to offset a parenthesis (i.e., dashes, brackets, or commas) are called parentheses.
Examples (with each example of parenthesis shaded):
Read more about using commas to replace brackets
Using Commas in Lists
When writing a list in "sentence form" (i.e., not as bullet points), then it is normal practice to separate the list items using commas. For example:
The first part of the rule is easy enough: when there are just two items in a list, there is no need to use a comma between them.
Read more about using commas in lists
Using Commas after a Long Subject
When the subject of a sentence is made up of lots of elements, it is known as a compound subject. For example:
Using Commas with Numbers
Commas can be used every 3 decimal places in large numbers to make them more readable. For example:
Using Commas before Speech Marks
Words like He said, She shouted, The author stated, and She wrote often precede a quotation. A comma can be used after these words to separate them from the quotation. For example:
In fact, it's your choice whether you follow your introductory words with a comma, a colon, or nothing. It depends on your desired flow of text. If you don't really care about the desired flow of text and you'd like some guidelines to help you decide which to use, then there is a useful guideline which states that a comma should be used for short quotations (six words or fewer) and colon should be used for longer quotations. (This is not a rule. It's a useful guideline.)
Read more about using a comma before speech marks
Using Commas with the Vocative Case
When words are used to address somebody (or something) directly, those words are said to be in the vocative case. In English, the vocative case is shown by offsetting it from the rest of the sentence with a comma (or commas if it's in the middle of the sentence). In the examples below, the words in the vocative case are shaded:
A READING TECHNIQUE NOT A WRITING TECHNIQUE
At school, many of us were told that a comma is where you take a breath. When you're reading someone else's work, that is fairly good advice. It is, however, terrible advice when you're thinking about where to put commas in your own work.
The rules for using commas are listed above (and on the left in more detail). There are quite a few of them, but most of them are intuitive or pretty simple. The idea that you should put a comma whenever you want your reader to take a breath is an erroneous extrapolation of a reading technique. It's not a writing technique.