Introducing English Linguistics

Conjunction.
Conjunction is different from the types of cohesion dis-
cussed so far. It does not depend on linguistic items occurring in the prior
context. Instead, it involves the inclusion of various kinds of expressions
that mark relationships between what occurred previously in a text and
what follows. In this sense, the expressions that are part of this type of
cohesion – words such as also or therefore and phrases such as on the other
hand – act as signposts, specifically marking how various segments of the
text are logically related.
Although there are different ways to describe the relationships that
words within the category of Conjunction mark, Halliday and Hasan
(1976: 242–3) propose four different relationships: additive, adversative,
causal, and temporal. Within each of these general groups are a series of
grammatical items expressing different variations on how additive rela-
tions, for instance, can be expressed in texts.
In its purest form, addition is signaled in texts by the coordinating con-
junction
and and transitional expressions such as also and  in addition.
Additive and is particularly common in spontaneous dialogues; such dia-
logues are unplanned and and serves as a way for speakers to signal that
they are adding something new to what they said previously:
I’d always wanted to go to Australia. And I met this Australian in London