Hemicelluloses, comprising the non-cellulose cell wall polysaccharides of vegetative and storage tissues of annual and perennial plants, represent an immense renewable resource of biopolymers. They occur in a large variety of structural types and are accessible to chemical functionalization reactions. In light of this, the volume gives information of the state of the art focusing on new plant sources, isolation methods, and characterization of structural features, physicochemical and various functional properties. Attention has been paid to derivatives prepared from these polysaccharides and to application possibilities of hemicelluloses or hemicellulosic materials.