Ion transport refers to the movement of charged particles, or ions, across cell membranes. This process is essential for various cellular functions, including maintaining the cell's electrical balance, regulating pH levels, and facilitating communication between cells. Ions such as sodium (Na+), potassium (K+), calcium (Ca2+), and chloride (Cl-) play crucial roles in these activities. There are two main types of ion transport: passive and active. Passive transport occurs when ions move along their concentration gradient without the use of energy, while active transport requires energy, often in the form of ATP, to move ions against their gradient. Both processes are vital for maintaining homeostasis in living organisms.