A cytokine receptor is a type of protein found on the surface of cells that binds to specific signaling molecules called cytokines. These receptors play a crucial role in the immune system by allowing cells to communicate and respond to various signals, such as inflammation or infection. When a cytokine binds to its receptor, it triggers a series of cellular responses that help regulate immune functions and maintain homeostasis. Cytokine receptors are diverse and can be classified into different families based on their structure and function. Some well-known families include the IL-2 receptor family and the TNF receptor family. Dysregulation of cytokine receptors can lead to various diseases, including autoimmune disorders and cancers, highlighting their importance in health and disease.