A chloride channel is a type of protein found in cell membranes that allows the passage of chloride ions (Cl⁻) into and out of cells. These channels play a crucial role in maintaining the cell's electrical balance and regulating various physiological processes, such as muscle contraction and nerve signaling. Chloride channels are essential for the function of many tissues, including the lungs and kidneys. Dysfunction in these channels can lead to various health issues, such as cystic fibrosis, which is caused by mutations in the CFTR chloride channel gene, affecting salt and water transport in the body.