In linguistics, information structure, also called information packaging, describes the way in which information is formally packaged within a sentence. This generally includes only those aspects of information that "respond to the temporary state of the addressee's mind", and excludes other aspects of linguistic information such as references to background (encyclopedic/common) knowledge, choice of style, politeness, and so forth. For example, the difference between an active clause (e.g., the police want him) and a corresponding passive (e.g., he is wanted by police) is a syntactic difference, but one motivated by information structuring considerations. Other choices motivated by information structure include preposing (e.g., that one I don't like) and inversion (e.g., "the end", said the man).
The basic notions of information structure are focus, givenness, and topic, as well as their complementary notions of background, newness, and comment respectively. Focus "indicates the presence of alternatives that are relevant for the interpretation of linguistic expressions", givenness indicates that "the denotation of an expression is present" in the immediate context of the utterance, and topic is "the entity that a speaker identifies, about which then information, the comment, is given". Additional notions in information structure may include contrast and exhaustivity, but there is no general agreement in the linguistic literature about extensions of the basic three notions. There are many different approaches, such as cognitive, generative or functional architectures, to information structure. The concept has also been used in studies measuring information density in cognitive linguistics.
