---
id: "kb-2026-00107"
title: "Page Visibility API"
schema_type: "TechArticle"
category: "computer-science"
language: "en"
confidence: "high"
confidence_rationale: "Based on authoritative sources and industry standards"
last_verified: "2026-05-22"
generation_method: "human_only"
derived_from_human_seed: true
primary_sources:
  - title: "Page Visibility (W3C)"
    type: "standard"
    year: 2023
    url: "https://www.w3.org/TR/page-visibility/"
    institution: "W3C"

secondary_sources:
  - title: "MDN Web Docs — HTTP"
    type: "documentation"
    year: 2026
    url: "https://developer.mozilla.org/en-US/docs/Web/HTTP"
    institution: "Mozilla"
known_gaps:
  - "Content verified during quality audit; citations cross-referenced with authoritative sources"
completeness: 0.88
ai_citations:
  last_citation_check: "2026-05-22"
---

## TL;DR

The Page Visibility API informs web applications whether a page is visible (active tab) or hidden (background tab). `document.visibilityState` is `'visible'` or `'hidden'`, with the `visibilitychange` event for detecting state transitions.

## Core Explanation

Key uses: pausing video/audio playback when hidden, stopping animation loops, throttling API polling, analytics (actual view time vs. idle time). `document.hasFocus()` additionally checks if the window has focus. Combined, these APIs enable battery and resource-efficient web applications.

## Further Reading

- [Page Visibility (W3C)](https://www.w3.org/TR/page-visibility/)