Cell signaling is the process by which cells communicate with each other to coordinate their functions. 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. There are several types of cell signaling, including autocrine, paracrine, and endocrine signaling. In autocrine signaling, a cell responds to signals it produces itself. In paracrine signaling, signals affect nearby cells, while in endocrine signaling, hormones travel through the bloodstream to reach distant target cells.