Book excerpt: Functional membranes are used in food processing, sensor technology, medical and biomedical devices, desalination, waste water treatment, CO2 capture, energy production and energy storage, optoelectronics etc. The book reviews recent advances in the field and discusses challenges and perspectives. Keywords: Membrane Fabrication, Polymer Membranes, Self-Assembled Membranes, Molecular Probes, Membrane Fouling, Membrane Cleaning, Microfiltration, Ultrafiltration, Food Processing, Sensors, Medical Devices, Biomedical Applications, Desalination, Wastewater Treatment, Ion Exchange Processes, Polymeric Ceramic Membranes, Nano Holes, Fuel Cells, Lithium-Ion Batteries, Optoelectronics.