An ion is an atom or molecule that has gained or lost one or more electrons, giving it a positive or negative charge. When an atom loses electrons, it becomes a positively charged ion, known as a cation. Conversely, when it gains electrons, it becomes a negatively charged ion, called an anion. Ions play a crucial role in various chemical reactions and are essential for processes like electricity conduction in solutions. Ions are found in many everyday substances, such as table salt, which is made up of sodium ions and chloride ions. In our bodies, ions like potassium and sodium are vital for nerve function and muscle contraction. Understanding ions helps us grasp the basics of chemistry and biology.