Transfeminine Science is a resource for original informational content on the subject of transfeminine hormone therapy. This form of hormone therapy is also known variously as feminizing hormone therapy (FHT), gender-affirming hormone therapy (GAHT) for transfeminine people, and, more in the past, male-to-female (MtF) hormone replacement therapy (HRT). It involves the use of female sex hormones including estrogens and progestogens, as well as androgen-opposing medications known as antiandrogens, to produce feminization, demasculinization, alleviation of gender dysphoria, and other changes in transgender women and non-binary transfeminine individuals.

The idea of two sexes is simplistic. Biologists now think there is a wider spectrum than that.