Estrogen pills are commonly used to supplement or replace estrogen levels in the body. They are often prescribed to women experiencing menopause symptoms, hormonal imbalances, or certain reproductive health conditions. These pills work by increasing estrogen levels, which can help regulate menstrual cycles, improve bone health, and reduce symptoms such as hot flashes or mood swings. However, estrogen pills should only be taken under medical supervision, as improper use can lead to side effects such as blood clots or an increased risk of certain cancers.