Words and expressions in language often derive some part of their referential meaning from indexicality. For example, "I" indexically refers to the entity that is speaking; "now" indexically refers to a time frame including the moment at which the word is spoken; and "here" indexically refers to a locational frame including the place where the word is spoken. Linguistic expressions that refer indexically are known as deictics, which thus form a particular subclass of indexical signs, though there is some terminological variation among scholarly traditions.