  In philosophy, intentionality is the power of minds and mental states to be about, to represent, or to stand for, things, properties and states of affairs. To say of an individual’s mental states that they have intentionality is to say that they are mental representations or that they have contents. Furthermore, to the extent that a speaker utters words from some natural language or draws pictures or symbols from a formal language for the purpose of conveying to others the contents of her mental states, these artifacts used by a speaker too have contents or intentionality. ‘Intentionality’ is a philosopher’s word: ever since it was introduced into philosophy by Franz Brentano in the last quarter of the nineteenth century, it has been used to refer to the puzzles of representation, all of which lie at the interface between the philosophy of mind and the philosophy of language. A picture of a dog, a proper name (e.g., ‘Fido’), the common noun ‘dog’ or the concept expressed by the word can mean, represent, or stand for, one or several hairy barking creatures. A complete thought, a full sentence or a picture can stand for or describe a state of affairs. How could some of the represented things (e.g., dinosaurs) be arbitrarily remote in space and time from the representation (e.g., a human thought or utterance about dinosaurs tokened in 2018), while others (e.g., numbers) may not even be in space and time at all? How could some representations (e.g., direct quotations such as ‘dinosaur’) even stand for themselves? How does a complex representation (e.g., a complete thought or a full sentence) inherit its meaning or content from the meanings or contents of its constituents? How should one construe the relationship between the iconic content of pictorial representations and the conceptual content of proposition-like representations (thoughts and utterances)? How should one understand the relation between the content of an individual’s mental state and the meanings of external symbols used by the individual to express her internal mental states? Are representations of the world part of the world they represent? Do all of an individual’s mental states have intentionality or only some of them? The entry falls into ten sections:  