Receptors are specialized proteins located on the surface of cells or within them. They play a crucial role in how cells communicate with their environment by detecting specific molecules, such as hormones or neurotransmitters. When a receptor binds to its target molecule, it triggers a response within the cell, leading to various biological effects. There are different types of receptors, including G protein-coupled receptors, ion channel receptors, and nuclear receptors. Each type has a unique structure and function, allowing cells to respond to a wide range of signals. This process is essential for maintaining homeostasis and regulating bodily functions.