Cell signaling pathways are complex networks of interactions that allow cells to communicate with each other and respond to their environment. These pathways involve various molecules, such as hormones, neurotransmitters, and proteins, which transmit signals from one cell to another. When a signaling molecule binds to a receptor on a target cell, it triggers a series of biochemical reactions that can lead to changes in cell behavior, such as growth, division, or apoptosis. These pathways are essential for maintaining homeostasis and coordinating functions in multicellular organisms. They can be categorized into different types, including endocrine, paracrine, and autocrine signaling, depending on the distance over which the signals act. Disruptions in cell signaling pathways can lead to various diseases, including cancer and diabetes.