An estrogen receptor is a type of protein found in various tissues throughout the body that binds to the hormone estrogen. This binding activates the receptor, allowing it to influence gene expression and regulate various biological processes, including reproduction, bone health, and cardiovascular function. There are two main types of estrogen receptors: ERα and ERβ, each playing distinct roles in the body. Estrogen receptors are crucial for normal development and function, particularly in the female reproductive system. They also have implications in certain health conditions, such as breast cancer, where the presence of estrogen receptors can affect treatment options and outcomes. Understanding these receptors helps in developing targeted therapies.