A period is the part of the menstrual cycle when a woman bleeds from her vagina for a few days. For most women this happens around every 28 days, but it's common for periods to be more or less frequent than this, ranging from every 21 days to every 35 days. There are many physical and emotional changes that can signal that your period is on the way, including tender breasts, mood changes, and tiredness. While we all experience symptoms differently, most women start to notice these symptoms between one and two weeks before they get their period [1]. Menstruation is the most visible phase of the menstrual cycle and its beginning is used as the marker between cycles. The first day of menstrual bleeding is the date used for the last menstrual period (LMP). Understand how to track your menstrual cycle and what to do about irregularities. Do you know when your last menstrual period began or how long it lasted? If not, it might be time to start paying attention. When you track your menstrual cycles, you learn what's typical for you. Menstruation (or period) happens monthly. As the uterus sheds its lining, vaginal bleeding follows. Menstrual blood is made of blood and tissue. Menstruation — aka having your period — is when blood and tissue from your uterus comes out of your vagina. It usually happens once every month. What is a normal menstrual cycle? Your period — and the PMS symptoms that can accompany it — is just one part of your monthly menstrual cycle. This disambiguation page lists articles associated with the title Period. If an internal link incorrectly led you here, you may wish to change the link to point directly to the intended article. period, epoch, era, age mean a division of time. period may designate an extent of time of any length. epoch applies to a period begun or set off by some significant or striking quality, change, or series of events. era suggests a period of history marked by a new or distinct order of things. Learn what periods are, when they start, and how they happen. Also, get tips about cramps, PMS, and period products.