information structure

Information structure marks how a proposition is packaged for a particular discourse context, independent of the proposition's truth-conditional content. A topic marking signals what the utterance is about, typically a referent already established or inferable in the discourse that the rest of the utterance is understood to add information to. A focus marking signals the part of the proposition that is not already presupposed by the addressee, the part where the assertion actually differs from what came before it. Many languages draw this distinction through word order or through prosodic prominence rather than through dedicated morphology, and prosodic marking of focus in particular is available in some form in nearly every language, which is one reason overt morphological marking of information structure is less common cross-linguistically than marking of a more familiar dimension such as number or tense.