> ## Documentation Index > Fetch the complete documentation index at: https://evalgate.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # Create a monitor > Define what to sample and how to score it. # Create a monitor A Continuous Eval monitor watches live traffic, scores a sample of it, and alerts you when quality slips. It lives at `/online-evals`. ## Step 1 — Start from a query The best monitors start from a real failure query. In the [Logs explorer](../traces/explore-logs), build the query that defines the traffic you care about, then click **Create draft monitor**. A screenshot of the Logs explorer with the Create draft monitor button. ## Step 2 — Define the sample and scorer On the monitor draft page: 1. Set the **sample rate** or **filter** that selects which traces to score. 2. Pick the **scorer** (calibrated, ideally) that decides pass/fail. 3. Set the **alert threshold** — for example, alert if the failure rate over the last 100 samples exceeds 5%. A screenshot of the monitor draft with sample, scorer, and threshold fields. ## Step 3 — Simulate on history Before the monitor touches live traffic, **simulate** it against historical traces. This proves the scorer and threshold behave the way you expect on real data. A monitor that has only been simulated is **not** active. It will not alert anyone until you explicitly activate it. ## Step 4 — Save the version Save the monitor version. Versions are immutable; changes create a new version that you simulate and activate again. ## Up next [Simulate, then activate](./activate-monitor) the monitor.