Deprecated standalone reference guide. It is not wired into any subagent loading path. Summarizes key Google Search concepts, requirements, and best practices. Not a reproduction of Google's documentation; see Official Documentation Links at the bottom for full details.
Google Search operates in three stages: Crawling (Googlebot discovers pages by following links and reading sitemaps), Indexing (Google processes and stores page content, metadata, and signals in its search index), and Serving (when a user searches, Google's algorithms rank indexed pages by relevance, quality, and usability to return the most useful results). Pages must be crawlable and indexable to appear in search results.
Formerly known as "Webmaster Guidelines." Key requirements:
Google evaluates content quality through the E-E-A-T framework:
YMYL Note: "Your Money or Your Life" topics (health, finance, safety, legal) are held to the highest E-E-A-T standards. Inaccurate YMYL content can cause real-world harm, so Google applies stricter quality thresholds.
Scope note: E-E-A-T informs Google's core ranking and helpful-content systems broadly (not only YMYL), but Google never published a "December 2025 watershed" extending it to all competitive queries, nor per-industry traffic-drop figures — treat such claims as third-party interpretation, not Google fact.
Measured at the 75th percentile of real user data (field data).
| Metric | Good | Needs Improvement | Poor |
|---|---|---|---|
| LCP (Largest Contentful Paint) | ≤ 2.5s | 2.5s – 4.0s | > 4.0s |
| INP (Interaction to Next Paint) | ≤ 200ms | 200ms – 500ms | > 500ms |
| CLS (Cumulative Layout Shift) | ≤ 0.1 | 0.1 – 0.25 | > 0.25 |
Key facts: - INP replaced FID (First Input Delay) on March 12, 2024. FID was removed from Chrome's field-data tools (CrUX API, PageSpeed Insights) on September 9, 2024 (Lighthouse is a lab tool that never reported FID). Do NOT reference FID. - Core Web Vitals are a confirmed ranking signal (since June 2021) - Field data (CrUX) is preferred over lab data (Lighthouse) for assessment - Passing all three metrics at "Good" is the target
Measurement tools: - Google PageSpeed Insights (field + lab data) - Chrome User Experience Report (CrUX): field data - Lighthouse (lab data only) - Google Search Console Core Web Vitals report
<script type="application/ld+json"> tags in the <head> or <body>@context and @type propertiesGoogle Search Console notifications for violations. Common causes: - Unnatural links (buying/selling links): Disavow bad links, request reconsideration - Thin content: Add substantial unique value to affected pages - Cloaking/sneaky redirects: Remove deceptive serving, request reconsideration - User-generated spam: Moderate comments/forums, add nofollow to user links - Structured data issues: Fix misleading or spam markup
No manual notification, detected through ranking drops. Common causes: - Helpful Content System: Merged into Google's core ranking in March 2024: no longer a standalone system. Helpfulness signals are now evaluated within every core update. Low-value, AI-generated, or unhelpful content at scale still triggers demotions via core updates. - Core Updates: Broad quality reassessment across all signals - Spam Updates: Automated detection of spam patterns - Link Spam Updates: Devaluation of manipulative link patterns
Mobile-first indexing is the default for the indexed web and Googlebot Smartphone is the primary crawler (rollout completed 2024). A mobile version is not strictly required (Google says it is "very strongly recommended"); the real risk for desktop-only sites is content/parity loss, not hard exclusion.