PMS stands for Premenstrual Syndrome. It's a way that a woman's body get's rid of some excess things. What happens is that your stomach/bladder/womb (I don't know exactly what) gets rid of a thin layer of blood that lines it, because it is not needed (and is only needed when you're pregnant). It does this every month, for a bout a week, and causes stomach cramps, bloating, and a sudden craving for chocolate, oder other comfort foods. That is about the onnly way I can put that. Sorry if I offended any other girls Von typing this.
PMS stands for premenstrual Sydrome AKA period it's occurs every Monat for girls and it's sucks because blood comes out of our 'area' it usually last for 7 days (depending on genes) moodiest occurs usually because of the menstrual cramps.