Basic Punctuation

The Comma

The comma , is the weakest punctuation mark. It is used to clarify structure WITHIN sentences.

Commas are less used in English writing than they used to be, and unnecessary commas should be avoided. However, commas are often useful to indicate groupings of words within sentences.

The sentences you have just read are a case in point. Neither comma is essential, but both help to make the meaning of the sentence clearer.

The most important skill is to be able to distinguish between complete sentences and parts of sentences. A complete sentence must end with a full-stop. Using a comma where a full-stop is needed is a very common mistake.

Look at these sentences:

This is a complete sentence. It is about Sarah. It tells you what Sarah did. It begins with a capital letter and ends with a full stop.

Sarah gazed into the water.

Here we have two complete sentences:

Sarah gazed into the water. She was frightened.

These sentences must be separated by a full stop.

Sarah gazed into the water. She was frightened. is correct

Sarah gazed into the water, she was frightened. is incorrect

Here we have a single sentence which is about two things. The two parts are joined by the word although. No other punctuation is needed.

Sarah gazed into the water although she was frightened.

Commas are often used to separate groups of words in longer sentences or sentences with unusual structures.

In this sentence, the parts have been reversed:

Although she was frightened, Sarah did not run away.

In this sentence, the parts have been reversed and the first part is quite long:

Because she had only been living in the village for a few weeks, she did not know many people.

In this sentence various kinds of actions are described, but the person is only mentioned once. We therefore use commas, not full stops:

She took off her shoes, jumped into the water, grabbed the bundle and heaved it into the boat.

Many people think that this sentence is clearer if a comma is put before and but this is not essential. The meaning is clear enough without it.

In these sentences various actions are described, but the person is only mentioned once. There is no joining word. We therefore need commas whichever order the parts come in:

Thinking herself alone, she opened the letter. She opened the door, convinced that he was there.

She opened the letter, thinking herself alone. Convinced that he was there, she opened the door.

Addressing People

Commas separate the names of people who are being addressed.

Good evening, Mary.

This evening, ladies and gentlemen, our speaker is Dr James Dunn.

Descriptive Phrases

Commas are put round a descriptive phrase if it comes after the word it describes.

Athens, capital of Greece, hosted the Olympics.

John's brother Michael won the marathon.

Michael, John's brother, won the marathon.

Michael, who is John's brother, won the marathon.

In some sentences of the last type, punctuation can change the meaning of the sentence.

The dog, which was smaller than the cat, lost the fight.

The dog which was smaller than the cat lost the fight.

The first sentence involves 1 small injured dog, 1 large cat. The second sentence involves 1 small injured dog, 1 large cat and at least 1 dog larger than the cat.

The comma , is the weakest punctuation mark. It is used to clarify structure WITHIN sentences.

Commas are less used in English writing than they used to be, and unnecessary commas should be avoided. However, commas are often useful to separate words or phrases within sentences.

The sentences you have just read are a case in point. Neither comma is essential, but both help to make the meaning of the sentence clearer.

The most important skill is to be able to distinguish between complete sentences and parts of sentences. A complete sentence must contain a complete verb, such as looked or was running and end with a full-stop. Using a comma where a full-stop is needed is a very common mistake.

Look at these sentences:

This is a complete sentence. It has a subject Sarah. It has a complete verb, telling you what Sarah did. It begins with a capital letter and ends with a full stop.

Sarah gazed into the water.

Here we have two complete sentences each with a subject and a verb:

Sarah gazed into the water. She was frightened.

These sentences must be separated by a full stop.

Sarah gazed into the water. She was frightened. is correct

Sarah gazed into the water, she was frightened. is incorrect

Here we have a single sentence which contains two subjects and two verbs. The two parts are joined by the conjunction although. No other punctuation is needed.

Sarah gazed into the water although she was frightened.

A part of a sentence containing a subject and a verb is called a clause.

Commas are often used to separate clauses in longer sentences or sentences with unusual structures.

In this sentence, Sarah did not run away is the more important of the two clauses. It is called the main clause. The clause beginning with although is less important and is called a subordinate clause. When the subordinate clause comes first, it is usually separated from the main clause by a comma:

Although she was frightened, Sarah did not run away.

In this sentence, the subordinate clause, introduced by the conjunction because, comes first and is also quite long:

Because she had only been living in the village for a few weeks, she did not know many people.

In this sentence various kinds of actions are described, but there is only one subject. We therefore use commas, not full stops:

She took off her shoes, jumped into the water, grabbed the bundle and heaved it into the boat.

Many people think that this sentence is clearer if a comma is put before and but this is not essential. The meaning is clear enough without it.

In these sentences various actions are described, but there is only one subject and no conjunction. We therefore need commas whichever order the parts come in:

Thinking herself alone, she opened the letter. She opened the door, convinced that he was there.

She opened the letter, thinking herself alone. Convinced that he was there, she opened the door.

Addressing People

Commas separate the names of people who are being addressed.

Good evening, Mary.

This evening, ladies and gentlemen, our speaker is Dr James Dunn.

Descriptive Phrases

Commas are put round a descriptive phrase if it comes after the word it describes.

Athens, capital of Greece, hosted the Olympics.

John's brother Michael won the marathon.

Michael, John's brother, won the marathon.

Michael, who is John's brother, won the marathon.

In some sentences of the last type, punctuation can change the meaning of the sentence.

The dog, which was smaller than the cat, lost the fight.

The dog which was smaller than the cat lost the fight.

The first sentence involves 1 small injured dog, 1 large cat. The second sentence involves 1 small injured dog, 1 large cat and at least 1 dog larger than the cat.

The dog, which was smaller than the cat, lost the fight.

This kind of clause is called a relative clause.

The dog which was smaller than the cat lost the fight.

This is also a relative clause. Relative clauses of this type are sometimes called defining relative clauses because they give us information which is essential for defining the subject.

Exercise

Read the following paragraph and decide where the punctuation should go. Tap the dotted square at the end of each sentence to place a full stop. Place commas where necessary by tapping a dotted square twice. Tap a third time to remove the punctuation mark. Tap the word following a full stop to give it a capital letter.

as the screams continued Sarah's fear increased she wheeled around but there was no one in sight the noise must have come from the gulls when she turned back to the water however the bundle had vanished 

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