# Cohort

A group of users or customers who share a defined characteristic or starting event.

A group of users or customers who share a defined characteristic or starting event.

## An example

A team follows everyone who signed up in October to measure their later retention.

## Why it matters

Keep the grouping rule stable so changes in cohort quality are not confused with changes in measurement.


## Related terms
- [Active user](https://jolts.xyz/resources/glossary/active-user)
- [Lifetime value (LTV)](https://jolts.xyz/resources/glossary/lifetime-value)
- [Retention rate](https://jolts.xyz/resources/glossary/retention-rate)

## Next step

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