Iontophoresis is a technique that uses electrical current to transport charged molecules (usually drugs or ions) across skin or other biological membranes. The principle of iontophoresis is that like charges repel and opposite charges attract. When a current is applied to a solution containing charged particles, the charged particles are propelled towards the oppositely charged electrode. In iontophoresis, two electrodes are placed in contact with the skin or other biological membrane and a small electric current is passed through them. An electrode, called the active electrode, is usually placed over the area to be treated and contains a charged substance that needs to be delivered. Another electrode, called a dispersive electrode, is placed elsewhere in the body and serves to complete the circuit. As the current flows through the skin, the charged material is swept and propelled to the opposite electrode. The strength and duration of the electric current and the properties of the charged substance determine the rate and extent of drug delivery. Iontophoresis is commonly used in physical therapy, dermatology, and other medical fields to deliver drugs, local anesthetics, and other therapeutic agents directly to the site of injury or pain. It is a non-invasive and painless method of drug delivery that has proven effective in a variety of applications.