# Sessions per variant

Measure how many sessions each experiment variant generates.

> **Automatically tracked**
>
> The SDK automatically tracks the events that feed this widget.

This widget shows how many sessions (or visits) were assigned to each variant during your experiment.

It helps you confirm that traffic is being distributed according to the allocation settings you defined when creating the experiment.

> **Question: What's the difference between sessions and active users?**
>
> - **Active user**: Any visitor, human or bot, who accesses your site at least once in the selected time period. We count each unique visitor only once within that period, no matter how many returns or page views. Anonymous and identified versions of the same person are counted as different users. That is by design to track unique identities, not guessed matches.
> - **Session**: A visit to your site. It can include multiple page views and interactions. It starts when a visitor arrives and ends after 30 minutes of inactivity (by default). One active user can create multiple sessions in the same period.

## Metrics

![Sessions per variant widget](/assets/reference/analytics/experiment/sessions-per-variant.png)

The chart includes:

1. **Sessions per variant**\
   How many visits were impacted by each variant of your experiment.

## Interpretation

This chart helps you evaluate how much exposure your experiment is receiving and how it evolves over time.

It's normal for the distribution to not match your allocation settings exactly at first. As more sessions are collected, the distribution will converge toward your expected split.

### What the number tells you

Here are some common insights you can get from this widget:

- Distribution not matching your settings may indicate a configuration issue or simply that more data is needed. Check your allocation settings if the imbalance persists over time.
- Low session volume overall indicates limited reach. You may need to broaden your audience or reduce the number of variants to collect enough data.

## Explore

- [Events](/reference/event/overview#event-types): Learn how to track user events for analytics and personalization.
- [Audiences](/explanation/audience): Understand how to delivery content to specific groups of users.