Reference to information source may be accomplished with a variety of means, including verbs referring to reports, claims, or opinions, adverbs, parentheticals, prepositional phrases or particles. In about one quarter of the world’s languages, marking information source is obligatory. These languages have a grammatical category of evidentiality. Other languages have evidential extensions of non-evidential categories—such as conditional in French. These ‘evidentiality strategies’ share the evidential meanings and often give rise to grammatical evidentials. The term ‘evidential’ primarily relates to information source as a closed grammatical system whose use is obligatory. The term ‘information source’ relates to the corresponding conceptual category. Expressions related to information source are heterogeneous and versatile, and may allow more detailed specification of various degrees of assumption, inference, opinion than do grammatical evidential systems, and often reliability, and speaker’s evaluation of information. The paper focuses on various aspects of expressing information source across the world’s languages.