Cellular signaling is the process by which cells communicate with each other to coordinate their activities. This communication occurs through signaling molecules, such as hormones and neurotransmitters, which bind to specific receptors on target cells. This binding triggers a series of biochemical events inside the cell, leading to a response that can affect growth, metabolism, or immune responses. These signaling pathways are crucial for maintaining homeostasis and responding to environmental changes. For example, when insulin is released by the pancreas, it signals cells to take up glucose from the bloodstream, helping to regulate blood sugar levels.