A females menstrual cycle is her body’s natural cycle that enables sexual reproduction – it will happen during puberty and everyone is different. It might start at age 11, or it might not happen till age 15.
This part you might have learnt in Biology, but in case you haven’t yet, a cycle is generally around 28 days and starts on the first day of a period, ending the day before the next period starts.
A cycle is when a females ovaries release an egg in the hope that it will be fertilised by sperm to create a baby. Menstruation happens when the egg is not fertilised – the soft lining of the uterus is released and fluid including blood comes out of the vagina. This can last between two and seven days but, again, everyone is different.