Calcium signaling is a cellular process where calcium ions (Ca²⁺) act as important messengers within cells. When a cell receives a signal, such as a hormone or neurotransmitter, it can trigger the release of calcium from storage areas within the cell or allow calcium to enter from outside. This increase in calcium concentration can activate various proteins and enzymes, leading to specific cellular responses. Calcium signaling plays a crucial role in many physiological functions, including muscle contraction, neurotransmitter release, and cell growth. Disruptions in calcium signaling can lead to various health issues, making it a vital area of study in fields like neuroscience and cardiology.