Full Stops and Commas


As a general rule most people need to use full stops more often than they actually do. In fact we often use a comma when really we should be using a full stop.



We all know that full stops are supposed to come at the end of the sentence … but sometimes the tricky part is knowing exactly when a sentence is supposed to end.


To work out where a sentence is supposed to end, you need to know that sentences are built up out of clauses and that the most important thing in a clause is the verb. In fact, a clause only ever contains one main verb. For example, look at the clauses below. Notice that they have just one main verb.


James ate the apple

Kim threw water at Brad

Lucy ran away very fast        (note that sometimes verbs can be more than one word long!)




Because each example above contains only one verb then we know that each of these is a single clause. We can now build up some sentences out of these three clauses.


Simple Sentences:

The most basic kind of sentence is called a simple sentence and these contain only one clause. So, ‘James ate the apple.’ is a complete simple sentence which is why it has a full stop at the end.


Compound Sentences:

However, we often want to join more than one clause together into what’s called a compound sentence and in order to do this we need to use a conjunction like ‘and’, ‘but’ or ‘or’. So, ‘Kim threw water at Brad and Lucy ran away very fast.’ is a compound sentence … and again, because it is a complete sentence, it needs to have a full stop at the end.


Complex Sentences:

The final kind of sentence that we can build up out of clauses is called a complex sentence and we make these by combining two clauses together using connectives like ‘which’, ‘because’ or ‘after’. So, ‘Lucy ran away very fast because Kim threw water at Brad.’ is a complete complex sentence, as is ‘Kim threw the water at Brad after James ate the apple.’ Hence they both need a full stop at the end.




Where people often go wrong is that they use commas to join clauses together which is not really what commas are supposed to do. The only way to join clauses together is to use a conjunction or a connective. If you don’t want to use one of these then you have to use a full stop. So, for example:


‘She ran out into the rain, he watched her go heartbrokenly.’ is not grammatically correct.


We know that ‘She ran out into the rain.’ is a clause because it has just one verb.

We also know that ‘He watched her go heartbrokenly.’ is a clause because it has just one verb.


So the only way to join these clauses together is by using a full stop, conjunction or connective. So, for example:


‘She ran out into the rain. He watched her go heartbrokenly.’  or

‘She ran out into the rain and he watched her go heartbrokenly.’  or

‘She ran out into the rain while he watched her go heartbrokenly.’ are all grammatically fine.




For many of you this will raise the question, ‘Well … when can I use a comma?’ There are many answers to this but basically, there are five situations when it is really safe for you to use a comma and these are:

1)       in lists

2)       after connectives like, ‘However,’ ‘Similarly,’ or ‘Moreover,’

3)       after other introductory remarks like, ‘In the summer of 2011, I went hiking.’

4)       in pairs to separate out some information from the main sentences, e.g.:

‘The man, who was very hungry, ate the baby.’

‘The car, which was red, exploded.’

5)       before quotations.