# Known users

> Follow signed-in people across days and devices with your own user id, and download or erase one person's events when they ask.

Source: https://docs.bifrostorbit.com/insights/everyone/known-users/

Without known users, Insights Orbit recognises a visitor for one day only and keeps nothing that points to a person. A website or app where people sign in can also send its own user id, such as a customer number, so the same person is followed across days and devices. That is personal data, and your organisation is responsible for it. Known users come with the Enterprise plan.

## Switch it on

1. Open the site, then **Site settings**.
2. Switch on **Accept user ids from the website** under **Known users**, then **Save settings**.
3. Have your developers send the id after someone signs in, with `insights.identify('customer-1042')` and `data-known-users` on the script, or `userId` with events your server sends.

Ids sent while it is off are dropped. Known users still need no cookie: the id comes from your own sign-in.

## How ids are kept

Insights Orbit never stores the id itself. It keeps a scrambled form made with a key that belongs to your organisation, so:

- nobody can read the id back from the events, the raw event API or the S3 export, where events carry the scrambled form as `person`
- the same id gives a different scrambled form in another organisation, so people can't be matched across organisations
- erasing your organisation throws the key away with the events

It is still personal data, because you can match it with the id you sent. Use ids that mean nothing outside your systems, such as a customer number, rather than email addresses.

## What it adds

- **Funnels:** choose **Known users, across days** on a funnel to count people instead of visits, so a step taken on another day or device still counts.
- **Retention:** see who comes back, week after week. See [Retention](https://docs.bifrostorbit.com/insights/everyone/retention/).

## Download or erase one person's events

When someone asks for their data or to be forgotten, an Admin can answer it:

1. Open **Known users** under **Organisation**.
2. Enter the user id your website sends for them, then **Look up**. You see how many events Insights Orbit keeps for them, when and on which sites.
3. Select **Download their events** for a file with one event per line, or **Erase their events** and type the id to confirm.

Erasing deletes their events and visits on every site at once and can't be undone. Totals in reports, such as how many people visited on a day, stay as they are, because they say nothing about one person. Every download and erasure is in the [audit trail](https://docs.bifrostorbit.com/insights/everyone/audit-trail/).

You can still download or erase events after your plan changes, for as long as any are kept.