We present a concise review of telechelic polymers of various architectures, focusing on the structure, solute solvent interactions, equilibrium and dynamical properties and applications. Telechelics are macromolecules with functionalized, mutually attractive groups, which assume a variety of conformations that depend on solvent quality, salinity and pH of the solvent, as well as on the macromolecular architecture. In concentrated solutions, telechelic polymers offer unique possibilities to create novel materials with distinct logical properties. Depending on chemistry and architecture, they can create percolating clusters and transient gels or they can show scopic phase separation into a dilute and a structured dense phase. The possibility to externally steer the morphology of these structures the concomitant physical properties of the materials renders telechelic polymers into important and versatile building blocks for materials science. (c) 2007 Elsevier Ltd. All rights reserved.