Ion Channels are pore-forming proteins that allow the selective passage of ions through plasma or intracellular organelle membranes based on an electric gradient. In addition to transducing electrical currents in the body, they play a role in cellular signaling, pH regulation, and cell volume regulation. Ion channels can be defined by what opens and closes the channel: voltage-gated channels open and close based on the voltage gradient across the plasma membrane or ligand-gated channels by the binding of various ligands to the channel. They are also be defined by the type of ion that selectively passes through (calcium, sodium, potassium etc.) or by the physical stimulation that opens or closes them (mechanosensitive, light sensitive, or temperature sensitive). Many disease states are caused by perturbed ion channel function (channelopathies) including epilepsy, cystic fibrosis, long QT syndrome, and various musculo-skeletal disorders. Pharmacologic manipulation of ion channels is widely used to treat cardiovascular disorders, pain, diabetes, constipation and is being investigated for use in cancer, inflammation, immunomodulation, kidney diseases and infection.