Commas before conjunctions (and, or, but)


Commas before conjunctions (e.g., and, or, but)

When a word like 'and', 'or' and 'but' (called conjunctions) joins two standalone sentences, you should put a comma before it.

Put a Comma before a Conjunction If It Joins Two Independent Clauses

Words like 'and', 'or' and 'but' are known as 'conjunctions'. (There are other conjunctions, but these 3 are by far the most common.)

Conjunctions are often used in lists, and the ruling about when to use a comma before a conjunction in a list depends on whether you're following US or UK writing conventions. However, this page is about conjunctions that are used to merge two sentences into one. This is a very common practice. When a conjunction is used in this way, it should have a comma before it.

Examples:

He is a great swimmer, but he prefers to play golf.

("He is a great swimmer." + "He prefers to play golf.")
(This is two sentences merged into one with "but" - comma required.)

comma before "and" in "vitamin, and the skin..." (This is correct.)
(magazine article)

I may consider your plan, or I may disregard it.

("I may consider your plan" + "I may disregard it." - comma required)

The female applicant must be able to tell jokes and sing, and she must be
able to dance.

("The female applicant must be able to tell jokes and sing." + "She must be
able to dance." - comma required)

The female applicant must be able to tell jokes, sing, and dance.

(This conjunction is not joining two sentences. Therefore, a comma is not required after "sing" if you're following UK conventions. In the US, the comma would be okay.)

PLC provided the material, and we built the road.

Drink is the curse of the land. It makes you fight with your neighbor. It makes you shoot at your landlord and it makes you miss him.

("It makes you miss him." is a sentence - comma required before "and")

A little dog can start a hare, but it takes a big one to catch it.

Basically my wife was immature. I'd be at home in my bath, and she'd come in and sink my boats. (Woody Allen)

I have nothing to offer but blood, toil, tears, and sweat.

(Winston Churchill)
(There is no need for the comma before "and" - "sweat" is not a sentence.)

The play was a great success, but the audience was a disaster.

(Oscar Wilde)

We make a living by what we get, but we make a life by what we give.

(Winston Churchill)

It is also worth knowing this:

If the two "sentences" (known as independent clauses) are very short, it is possible — for style purposes — to omit the comma.

TOO MANY COMMAS?

When sentences containing commas are merged together using a conjunction, it is possible to use a semicolon instead of a comma. (See lesson Semicolons for more examples.) However, this is quite an outdated practice in modern writing. Use it very sparingly - if at all.

Last year, PLC provided the material; and we, L&S Ltd, built the road.