Some basic body literacy:
A proper period or menstrual bleed is a bleed at the end of a natural ovulatory cycle. Any other type of bleed is either a pill bleed (a withdrawal bleed from stopping contraceptive drugs) or an anovulatory cycle (a bleed when there has been no ovulation).
A menstrual cycle is, therefore, an “ovulatory cycle,” in which ovulation is the main event.
What else you need to know
⭕ Ovulation comes first, and then a period almost exactly two weeks later.
⭕ You can confirm ovulation by tracking basal body temperatures.
⭕ If you don’t ovulate but still bleed, it’s an anovulatory cycle.
⭕ If you don’t bleed, you’re either not ovulating or you’re pregnant.
⭕ It’s (usually) not possible to ovulate but then not get a period or be pregnant. (Except in the case of hormonal IUD, hysterectomy, or ablation.)
⭕ When you come off the pill, you can become pregnant without ever seeing a bleed because ovulation comes first and then the bleed. That’s why you need to take some action to avoid pregnancy (barrier or withdrawal method) even before you get your period back.
⭕ Bleeds on progestin-only methods are usually anovulatory. Except with the hormonal IUD, in which case, your cycles could be ovulatory, even if you don’t bleed.
Have I missed anything? Add it to the comments.