---
title: "Visual Regression — monitoring glossary"
description: "A visual regression is an unintended visual change to a webpage — a button moved, text colour changed, a section disappeared, an image broken — caused by a…"
canonical: "https://lemwatch.com/glossary/visual-regression"
source: "https://lemwatch.com"
---

# Visual Regression

> A visual regression is an unintended visual change to a webpage — a button moved, text colour changed, a section disappeared, an image broken — caused by a code or content update. Visual regression testing automates the detection of these changes.

## Definition

 A visual monitor captures a screenshot of each tracked page on a schedule (or after every deploy), then pixel-diffs the new image against the previous baseline. Significant differences are flagged for human review with the changed regions highlighted.

 Good visual monitoring includes ignore-zones (for ads, timestamps, A/B test variants that legitimately change), responsive variants (desktop + mobile + tablet), and authenticated states (post-login screens).

## Why it matters

 Many of the worst production bugs are visual — a CSS change that hides the buy button, a CMS edit that removes the pricing section, an A/B test that breaks the navigation. Functional tests miss these. Visual regression catches them within minutes.

 See it in the product: [Visual monitoring](https://lemwatch.com/features).


## Related

- [Monitoring glossary](https://lemwatch.com/glossary)
- [Change Detection](https://lemwatch.com/glossary/change-detection)
- [Money Page](https://lemwatch.com/glossary/money-page)
- [All monitoring checks](https://lemwatch.com/features)
- [Alert Fatigue](https://lemwatch.com/glossary/alert-fatigue)
- [Uptime](https://lemwatch.com/glossary/uptime)