Estrogen Receptor Beta (ERβ) is one of two main types of estrogen receptors in the body, the other being Estrogen Receptor Alpha (ERα). These receptors are proteins that bind to the hormone estrogen, allowing cells to respond to its signals. ERβ is primarily found in tissues such as the brain, bones, and reproductive organs, playing a crucial role in regulating various physiological processes. ERβ is involved in functions like bone density maintenance, reproductive health, and cardiovascular function. It also has implications in certain diseases, including breast cancer and prostate cancer, where its activity can influence tumor growth and response to treatments.