Ross E. Sager and Jung-Youn Lee Plasmodesmata are cytoplasmic communication channels that are vital for the physiology and development of all plants. They facilitate the intercellular movement of various cargos – ranging from small molecules, such as sugars, ions and other essential nutrients and chemicals, to large complex molecules, such as proteins and different types of RNA species – by bridging neighboring cells across their cell walls. Structurally, an individual channel consists of the cytoplasmic sleeve that is formed between the endoplasmic reticulum and the plasma membrane leaflets. Plasmodesmata are highly versatile channels; they vary in number and structure, and undergo constant adjustments to their permeability in response to many internal and external cues. In this Cell Science at a Glance article and accompanying poster, we provide an overview of plasmodesmata form and function, with highlights on their development and variation, associated components and mobile factors. In addition, we present methodologies that are currently used to study plasmodesmata-mediated intercellular communication.