HRT stands for hormone replacement therapy (you will also see "menopausal hormone therapy" or MHT in medical writing - same thing). The idea is in the name: through perimenopause and menopause, the ovaries wind down production of estrogen and progesterone, and the symptoms that follow - covered below - trace back to that decline.
HRT replaces what declined, at doses meant to relieve symptoms. One important scoping note: this article covers menopause-related HRT for women; testosterone therapy for men is a different treatment with its own rules - the differences are in is HRT the same as TRT.

