---
title: "Severity (SEV-1 to SEV-4) — Definition | FourSight Glossary"
url: https://foursight.cloud/glossary/severity
description: "A standardized scale for how serious an incident is. SEV-1 is a full outage; SEV-4 is cosmetic. Severity drives response time, who's paged, and whether …"
lang: en
---

Back to glossary: https://foursight.cloud/glossary

Incidents & On-Call

# Severity (SEV-1 to SEV-4)

A standardized scale for how serious an incident is. SEV-1 is a full outage; SEV-4 is cosmetic. Severity drives response time, who's paged, and whether status-page comms are required.

Source

- PagerDuty — Severity Levels (https://response.pagerduty.com/before/severity_levels/)

## Related terms

Incident

An unplanned event that disrupts service or threatens to.
https://foursight.cloud/glossary/incident

Incident Commander (IC)

The single person who owns coordination of an incident end-to-end.
https://foursight.cloud/glossary/incident-commander

Tech Lead (during incident)

The engineer actively diagnosing and fixing the problem during an incident.
https://foursight.cloud/glossary/tech-lead

Comms Lead

Owns customer-facing communication during an incident — status page updates, in-product banners, support te…
https://foursight.cloud/glossary/comms-lead

On-Call Rotation

A scheduled rotation of engineers who are responsible for responding to alerts outside business hours.
https://foursight.cloud/glossary/on-call-rotation

Escalation Policy

Rules that decide who gets paged next if the primary on-call doesn't acknowledge within a timeout.
https://foursight.cloud/glossary/escalation-policy

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