Hormone Replacement Therapy (HRT) is a medical procedure in which a transgender person takes hormones in order to alter their sex characteristics. It is commonly a part of a medical transition.
Hormones can be administered in many forms, which commonly include injections, transdermal patches or creams, and pills.
Transmasculine people typically take testosterone (sometimes called "T") during HRT, while transfeminine people take estrogen and may also take progesterone and/or anti-androgens.