Tip growth is a type of cellular growth that is represented in many and diverse cell types, which are important to plant breeding (pollen tubes), agriculture (root hairs) and plant and animal pathology (fungal hyphae). Also moss and fern protonemata as well as algal zygotes and yeasts exhibit the features unique for tip growth: directable apical linear growth which renders the cell able to penetrate its growth environment. In this volume various cell biological aspects of this particular growth phenomenon are discussed, such as the initiation and maintenance of an anisotropically growing cell, the function of cytoskeletal elements, extracellular matrix and turgor, the regulation of ion homeostasis, the mechanism of signalling events, and the interaction of the cell with the environment.