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Hormone Replacement Therapy, or HRT, is the process of taking hormones either orally or by injection. The act of replacing hormones that your body is no longer producing sufficiently, or adding hormones that your body does not produce at all, is a therapy used for many medical issues (most commonly, for treating menopause in older women).

For trans and gender-nonconforming people, it's often the first medical step to affirming one's gender identity. The supplementing of sex hormones — like estrogen, anti-androgens, or testosterone — allows an individual to develop physical characteristics that better match the gender they identify as.

For this post, Buzzfeed LGBT asked for some extra input from Dr. Meera Shah of the Callen-Lorde Community Health Center , and Dr. Asa Radix, MPH, senior director of research and education at Callen-Lorde.