pcos is polycystic ovary syndrome, which is really a misnomer because the ovarian cysts are a symptom of the syndrome, not the cause. Most people with pcos have insulin resistance, which wreaks havoc with normal hormone levels, which leads to various symptoms like irregular menstrual cycles, infertility, irregular hair growth, arcanthosis nigricans, cystic ovaries, a tendancy to gain weight really easily, recurrent miscarriages, acne etc etc etc. The symptoms are different for each person with pcos and vary in intensity from person to person.