Focus is used to convey new information. It is also defined as a linguistic expression identifying a set of alternatives which are relevant for its interpretation. This is demonstrated in the discourse reported below.
wh
A: ix2 buy qartichoke
foc
B: ix1 car new buy ix1
‘What did you buy?’ ‘I bought a new car.’
The focus item car automatically creates in the mind of the addressee a set of other alternatives (house, bike, pullover…), and among these unpronounced alternatives the focus is the one chosen. Depending on its scope, focus can be broad or narrow. Broad focus (PRAGMATICS 4.1.1) carries new information within the whole sentence, and it generally occurs as the answer to a general question like ‘What happened?’. Narrow focus (PRAGMATICS 4.1.2) concerns a single phrase (or sign). It can only introduce a piece of new information denoting a particular concept or entity, or it can have a contrastive or corrective meaning. If focus is corrective, it denies a previously mentioned item, substituting it with the correct one (PRAGMATICS 4.1.3). Another type of focus is emphasis. It highlights an item by repeating it at the end of the sentence, or by reinforcing it with a particular prosodic contour (PRAGMATICS 4.1.4). Finally, focus can also be doubled in order to place stress into a specific expression (PRAGMATICS 4.1.5).