What is Ovulation?

Ovulation is the part of the menstrual cycle when one of the ovaries releases an egg (an oocyte). It is during this process that the egg travels down the fallopian tube, and may be met by a sperm and become fertilized. 

When does it occur?
Ovulation usually occurs between 12 and 16 days before your period starts. This is an average, so it could be a couple of days earlier or later. Our average Cycler ovulates on CD 17. Your body releases LH to initialize ovulation. Read more about LH here.
What about multiple ovulations?
Multiple ovulations may occur, but the second ovulation will happen within 24 hours from the first one. This is as the progesterone released after the first ovulation inhibits a second ovulation from taking place. Read more.
What is anovulation?

Anovulatory cycles are cycles without ovulation. You can read more about anovulatory cycles here.