Ion Channels, from Fantasy to Fact in Fifty Years1 -- Specific Channel Types -- Gramicidin Channels: Versatile Tools -- Voltage-Gated Ion Channels -- Voltage-Gated Potassium Channels -- BKCa-Channel Structure and Function -- Voltage-Gated Sodium Channels -- Calcium Channels -- Chloride Transporting CLC Proteins1 -- Ligand-Gated Ion Channels: Permeation and Activation1 -- Mechanosensitive Channels -- TRP Channels -- Ion Channels in Epithelial Cells -- Theoretical Approaches -- Poisson–Nernst–Planck Theory of Ion Permeation Through Biological Channels -- A Mesoscopic–Microscopic Perspective on Ion Channel Permeation Energetics: The Semi-Microscopic Approach1 -- Brownian Dynamics: Simulation for Ion Channel Permeation1 -- Molecular Dynamics Simulation Approaches to K Channels -- Emerging Technologies -- Patch-Clamp Technologies for Ion Channel Research -- Gated Ion Channel-Based Biosensor Device -- Signal Processing Based on Hidden Markov Models for Extracting Small Channel Currents.