Cohesion: the essentials

What is cohesion?

Cohesion refers to the way ideas are linked together to make meaning and applies to both written and spoken language.

For example, look at the sentence and focus on the words in red and black.

John came into the house, walked through it and went into the garden where he picked two red roses and a yellow one.

The words in red are examples of cohesion in English and they link to the words in black. it refers to the house, and links the two actions, where links the garden to the action, one at the end tells us it's also a rose so we don't need to repeat the noun. We don't repeat John in walked through it because we know who did that so we can leave out the word (that's called ellipsis).

We could, of course, not use any of these clever devices to link things together and we often don't use them so much when we are speaking off the cuff and don't have time to think so we could rephrase the whole paragraph as:

John came into the house. John walked through house. John went into the garden. John picked two red roses in the garden. John picked a yellow rose in the garden.

but you will probably agree that without any cohesion, the paragraph is clumsy and childish. Children do, in fact, often talk and write like this because they have yet to learn more sophisticated ways to string ideas together.

A small technical note:
What we are talking about here is called reference (one thing referring to another). The thing referred to is called the referent so in, for example:
John talked to me
the referent of the word me is the speaker of this sentence.
In the example above, the word it is a reference to the house and the referent is the house.

Back and forth

You can see in the example sentence about John and the garden that the first pronoun, it, refers back to something we have already mentioned and leaving out John in the sentence is possible after the first time we mention him because we know that the subject is not changing. This is the usual way that referencing, i.e., one way of making a text cohesive, works.

We can refer back in a text like this:

This is called anaphoric referencing.

We have:

it
referring back to the house
This is pronoun referencing.
where
referring to in the garden
This is relative adverb referencing.
he
referring to John
This is also pronoun referencing.
one
referring to roses
This is also pronoun referencing.

It's also possible to refer forward in a text but that is rarer and gives a different, literary, feel sometimes.

This is called cataphoric referencing.

Here, we have:

he
referring forward to John
it
referring forward to the garden

Types of cohesion

Reference:: Often this is achieved through the use of pronouns such as he in the sentence about John above.
For a list of pronouns which can function to hold texts together (i.e., all of them), see the link to a PDF file at the end.
The pronoun refers either back or forward to the noun in sentences such as
    John didn't tell me where he is
    When she came in, I saw that Mary was very upset
Sometimes referencing is to a whole statement in examples such as
    As I mentioned earlier ...
    That is why ...
    This is what I said: ...
etc.
The use of referencing is the most common way to make texts hang together and it is widely used in both spoken and written language.
Here are some more examples:
    A: Where's the car
    B: I lent it to Mary?
    The bus broke down and that's why I'm late
    When I finally got round to reading them, I thought the books were really good
Ellipsis:: This means leaving out (ellipting is the technical term) a word because the reader / listener knows what the reference is. In the example above, we don't repeat John for the second verb. In spoken English, we very often get exchanges like
    A: What's for lunch?
    B: Cauliflower cheese (leaving out the clause, is for lunch)
Here are two more examples:
    A: Who arrived?
    B: John (ellipting the verb, arrived)
    I don't like the red shoes but I love the blue (ellipting the noun, shoes)
    He speaks good French and German (ellipting the verb speaks and the adjective good because we assume they both apply to French and German)
For more, go to the guide to substitution and ellipsis linked in the list of related guides at the end.
Substitution:: In this, we don't leave out the word but change it for something more general. For example, above, the use of one to mean a rose or in something like
    What wines do you want?
    I'll take the French stuff
We can also substitute other types of words, like this:
    Mary doesn't want to go but I do
in which do stands for want to go
    She thought it was boring but I didn't think so
where so stands for it was boring
    The food was wonderful and the wine, too
where too stands for was wonderful
Conjunction:: We use conjunction to join ideas (see the section on conjunctions in the guide to word class, linked in the list at the end) in both spoken and written English. For example, and went into the garden, above, or in exchanges like
    Why did you open the cage?
    Because I wanted to change the water
A special kind of conjunction, called a conjunct, is also something very commonly used in writing to link ideas together. For example:
    She came late to the meeting. Consequently, she missed the important introduction.
Lexical cohesion:: This refers to the fact that in any text (written or spoken) there are likely to appear chains of related words. For example, in a text about hospitals it is likely that nouns such as medicine, patient, nurse, ward, treatment and doctor will appear along with verbs such as treat, admit, operate, sterilise and care for.
We also sometimes use a word which means the same or a word which includes another one. For example:
    I cleaned the house, washed the car and did some other chores
where the word chores stands as a general term for cleaning, washing and so on. The hearer or reader is left to imagine that it might also include things like washing up, sweeping, shopping and so on but knows that it will not include things like going to work or planning a holiday because the meaning of the word chores does not usually include such matters.
Another example is:
    She gave him his allowance but he spent the money
in which money is a general term which includes allowance (and cash, coins, notes and so on).
Sometimes, we can use a synonym (a word which means more or less the same thing) to get the same linking, cohesive effect as in, e.g.:
   He tried to find the right volume but the book wasn't there
in which volume and book are synonyms.
Grammatical cohesion:: This refers to the fact that we employ similar grammar in texts to keep the theme, especially the tense, consistent. For example:
    He went into the bar, walked up to the counter and ordered three beers
    I will go to London and will see if I can meet him
Another very common form of grammatical referencing involves using words like who, which, where, when etc. to refer to something already mentioned. Here are some examples:
    That's the boy who stole my bicycle
    This is the restaurant where we met
    That's the car which hit the lamppost
    It was early in the morning when I went out
These are relative pronouns (the first and third examples) or relative adverbs (the second and fourth examples).

Here's an example of grammatical and lexical cohesion working together:

While we were on holiday in a Spanish resort we used to go to the beach every morning and then we'd have lunch in a little restaurant in town where the tourists didn't go very much. The food was fantastic and very cheap and the fish dishes in particular were wonderful.

The tenses are consistently in the past (underlined), the nouns related to food and restaurants are also present (in red) and there's a second lexical string concerning holidays (in green). The text also contains examples of other forms of cohesion. Spot them.

Click to take a test on this area.

Related guides
deixis	for a much more technical guide considering how we talk about not here, not now and not me
substitution and ellipsis	for a more technical guide to these two areas
pronoun list	this is a list in PDF format of the pronouns in English which act to hold texts together cohesively
word class	the essential guide which includes consideration of conjunctions and more

Reference:
Halliday, MAK and Hasan, R, 1976, Cohesion in English, London: Longman.