Learn about your cycle

A note before we start. Everything here is general information to help you understand your body. It isn't medical advice, and it isn't a diagnosis. Bodies differ, and most of what you'll read varies a lot from one person to the next. If something feels off for you, the right person to ask is a clinician who knows your history.

Questions about the app itself, where your data lives, what it costs, what it predicts, are in the FAQ.

This is the same guide that ships inside the app's Learn tab. Every claim about the body traces to a graded, sourced entry in our evidence notes, and where the science is thin we say so.

• Why so much of this was never studied

  If you've felt like no one ever properly explained your own body to you, you're not imagining it.

• What we won't do

  We won't hand you a meal plan or a workout that promises to "unlock" your hormones.

• How your cycle works

  A menstrual cycle runs from the first day of one period to the first day of the next.

• Your Inner Seasons

  How your cycle works covers the science. The Inner Seasons are how we translate it into something easier to live with, and each one lines up with…

• Understanding your cycle

  Your uterus is lined with tissue called the endometrium, and it has two layers. The deeper base layer stays in place all the time.

• Your body across the cycle

  Discharge is normal and healthy. It's how your vagina keeps itself clean and protected, and it changes across your cycle: drier and stickier after…

• Managing your period and contraception

  There's no single best product for everyone, and anyone who says there is is probably selling something. That doesn't make them all the same, though.

• Bodies and lives

  Bodies change over a lifetime, and no two are the same. This part covers both sides of that: the transitions your cycle moves through as you get…

• When something's worth checking

  Most cycle variation is completely normal, and this section isn't meant to make you anxious. If anything it's meant to do the reverse.

• Your data and privacy

  Health data about your cycle is sensitive, and where it lives matters. Since 2022 there's been real concern about period-tracking data being used…

• Sources

  Every paper behind the guide, grouped by topic, with links so you can check our work.