tell in details  what does periods mean....?
204364
From http://en.wikipedia.org/wiki/Menstrual_cycle\n\nOnly human beings and the great apes experience a true menstrual cycle. Most placental mammals experience estrus instead. The menstrual cycle is under the control of the reproductive hormone system and is necessary for reproduction. In women, menstrual cycles occur typically on a monthly basis between puberty and menopause.\n\nDuring the menstrual cycle, the sexually mature female body releases one egg (or occasionally two, which might result in dizygotic, or non-identical, twins) at the time of ovulation. The lining of the uterus, the endometrium, builds up in a synchronised fashion. After ovulation, this lining changes to prepare for potential implantation of the fertilized egg to establish a pregnancy. If fertilization and pregnancy do not ensue, the uterus sheds the lining and a new menstrual cycle begins. The process of the shedding of the lining is called menstruation. Menstruation manifests itself to the outer world in the form of the menses (also menstruum): essentially part of the endometrium and blood products that pass out of the body through the vagina. Although this is commonly referred to as blood, it differs in composition from venous blood.\n\nCommon usage refers to menstruation and menses as a period. This bleeding serves as a sign that a woman has not become pregnant. (However, this cannot be taken as certainty, as sometimes there is some bleeding in early pregnancy.) During the reproductive years, failure to menstruate may provide the first indication to a woman that she may have become pregnant. A woman might say that her "period is late" when an expected menstruation has not started and she might have become pregnant.\n\nMenstruation forms a normal part of a natural cyclic process occurring in healthy women between puberty and the end of the reproductive years. The onset of menstruation, known as menarche, occurs at an average age of 12, but can occur any time between the ages of 8 and 16.[1] However, the condition precocious puberty has caused menstruation to occur in girls as young as 8 months old. The last period, menopause, usually occurs between the ages of 45 and 55. Deviations from this pattern deserve medical attention. Amenorrhea refers to a prolonged absence of menses during the reproductive years of a woman for reasons other than pregnancy. For example, women with very low body fat, such as athletes, may cease to menstruate. The presence of menstruation does not prove that ovulation took place; women who do not ovulate may have menstrual cycles. Those anovulatory cycles tend to take place less regularly and show greater variation in cycle length. In addition, the absence of menstruation also does not prove that ovulation did not take place, because hormone disruptions in non-pregnant women can suppress bleeding on occasion.\n\nWomen show considerable variation in the lengths of their menstrual cycles, and the length of the menstrual cycle differs in different animals.\n\nWhile cycle length may vary, 28 days is generally taken as representative of the average ovulatory cycle in women. Convention uses the onset of menstrual bleeding to mark the beginning of the cycle, so the first day of bleeding is called "Cycle Day one".\n\nOne can divide the menstrual cycle into four phases:\n\nMenstruation\nEumenorrhea denotes normal, regular menstruation that lasts for a few days (usually 3 to 5 days, but anywhere from 2 to 7 days is considered normal.[2] The average blood loss during menstruation is 35 millilitres with 10-80 mL considered normal;[3] many women also notice shed endometrium lining that appears as tissue mixed with the blood. An enzyme called plasmin — contained in the endometrium — inhibits the blood from clotting. Because of this blood loss, women have higher dietary requirements for iron than do males to prevent iron deficiency. Many women experience uterine cramps, also referred to as dysmenorrhea, during this time
658569
Go to beinggirl.co.uk. They have lots of advice about periods. When you buy tampons they have instructions in the box so you don't have to worry about noot knowing what to do. When you start you should just use pads for a while to get used to it and move onto tampons if you want.
117775
You mean, for the first time? You don't know in advance, you will know when it comes.\nOnce you start having regular periods, just count days from the beginning of one period to the beginning of another for several months. The number of days will be around the same. Then you can look at your calendar and estimate the date of your next period.
17976
blood flows out, your weight or size basically determines if you get heavy periods or light periods. every 28 days from the last day of your period to the start of your next,some peoples last maybe less than 5 days and some others last up to 8 days, you get cramps, your lower back aches, sometimes you get bloated, u get tired, and thats all i can think of.
96129
During PMS or during your period?? Either one is ok and perfectly normal.
401626
well at the end of the day a womens body tells her when shes ready, she starts a period, but mature enough is another matter!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
131299
say something like  "so mom guess what? i got my period today" or "mom i think i started my period could we go buy some pads or something" tell her b4 u go to bed or right after school- DON'T WAIT because that's not safe
302037
Its short for emotional hun. Its not guys who dress up in girls clothes. It does refer to the type of clothes they wear though. I can't describe it exactly and the type of music they listen to. Its just another group, like goths , pikeys and chavs
75543
They refer to different phases of the moon.  The "waxing and waning"  moon.  Try this link:\n\nhttp://www.enchantedlearning.com/subjects/astronomy/moon/Phases.shtml
361258
It means your period is not on a monthly cycle. Count the days from the first day you start til the next day you start and keep a private record on a calendar. If you find they are not staying consistant let your doctor know you have irregular periods.
48581
If you are asking in context of a particular Black Eyed Peas song, it means any number of things sexually.  That should get you in the right direction.
577898
Having a period is your body's way of preparing for pregnancy.  The uterus lines itself up each month so that it is prepared for the fetus growing in it.  However, if you don't get pregnant, the lining will grow older and won't be as good for the fetus anymore.  Thus, your body has to get rid of the uterus lining and replace it with a fresh lining each month, just in case you get pregnant.
245091
It just means that she has something to talk to you about. Ask her what she wants to talk about.
326365
It has nothing to do with your period. I assume you are still young. At your age your period will not be completely regular yet. For a lot of woman their period will never be completely regular. Don't worry about it.
264387
It means either strange, promiscuous or sexually...hmm...experiemntal I guess is the most polite way of wording it.
169552
Are you under stress? That can stop periods
396633
Since you have recently started menstruation, periods may be irregular particularly during the first year. Not every woman has a 28 day cycle and that's counting from the first day of the period. Now that you have started though you could see a gynecologist (women's doctor) to get some insight on what is normal for you...\nGood luck...