What are conjunctions? Conjunctions join words or groups of words together. The most common ones are and, or, and but.
There is no simple rule about whether you should use a comma before a conjunction. The rules on that are quite complicated (covered below).
You can start a sentence with a conjunction, but you shouldn't do it too often.
What Are Conjunctions?Conjunctions are used to join words or groups of words together. The most common ones are and, or and but. (There are others – see Conjunctions in the Glossary of Terms.)
Conjunctions can be categorized into one of three groupings:
Coordinating ConjunctionsCoordinating conjunctions are the ones which tend to spring to mind when people think about conjunctions. They include and, but, or, nor, for, so and yet. They are used to join individual words, phrases and independent clauses.
Coordinating Conjunctions Joining Individual Words:
Correlative ConjunctionsCorrelative conjunctions appear in pairs. For example, either...or, neither...nor, whether...or and not only...but also.
Subordinating ConjunctionsSubordinating conjunctions include: after, although, as, because, before, if, once, since, than, that, though, till, until, when, where, whether and while.
They are used to show the relationship between the independent clause and the dependent clause.
Click on the coordinating conjunctions:
Errors with ConjunctionsConjunctions do not normally cause serious errors, but writers are sometimes confused about when to place a comma before a conjunction. Unfortunately, there is no simple rule, such as: Never put a comma before and.
The guidelines are explained in the lesson Conjunctions and Commas.
Comma before And in a List?Most lists look like this:
The conjunction sits before the final thing. In this case, it's the word and. The big question is whether the comma before the and is right or wrong.
When there are just two list items, there is no need for a comma before the conjunction. For example:
However, when there are more than two list items, the world is divided on whether there should be a comma. There is no right answer. You have to pick a convention and stick with it.
The comma before the conjunction is called an Oxford Comma. Some people consider the Oxford Comma to be a waste of ink, while others strongly campaign for its inclusion. In general terms, the Oxford Comma is more common in the US than it is in the UK (despite it being called the Oxford Comma).
There is another quirk. On occasion, it may be appropriate to use a comma with the conjunction in a simple list (even a list with just two list items). This could be for the sake of tidiness or to eliminate ambiguity. (This topic is also covered in the lesson Commas in Lists.)
the and makes it easier for the reader to identify the last list item.)
STARTING A SENTENCE WITH A CONJUNCTION
In the past, schools were rigid in their ruling that sentences could not start with conjunctions, such as And or But. However, nowadays, this practice is considered acceptable.
The two most common conjunctions used in this way are And (meaning In addition) and But (meaning However). It is usual to follow each with a comma.
Whilst it is acceptable to use And or But to start a sentence, this practice should be limited and only used for impact or to control the flow of text. If you find yourself using them too often, you should consider changing the style of your writing. Starting your sentences with conjunctions will annoy your readers if you do it too often.