 Kaplan distinguishes two different aspects of the meaning of expressions in a public language. The first aspect, content, reflects the modal profile of the object, kind or property represented. This is the aspect of meaning that is modeled by standard possible world semantics. The second aspect of meaning, character, reflects semantic rules governing how the content of an expression may vary from one context of use to the next. A context-invariant expression like ‘Hillary Clinton’ has a constant character, picking out the very same object in every context in which it’s used, whereas indexical expressions like ‘I’ or ‘this’ have variable character, picking out different things in different contexts of use.