---
type: Index
title: "Glossary"
description: "Index of glossary concepts in this OKF bundle."
timestamp: 2026-05-11T00:00:00Z
---

# Glossary

- [AI Overviews](/glossary/ai-overviews.md) — Google's AI-generated answer block that appears above traditional search results.
- [Answer Engine Optimization (AEO)](/glossary/aeo.md) — Optimizing content to be cited inside AI-generated answers.
- [Canonical tag](/glossary/canonical-tag.md) — An HTML hint that tells search engines the preferred URL for a piece of content.
- [ClaudeBot](/glossary/claudebot.md) — Anthropic's crawler. Used for training and Claude product context.
- [Cloaking](/glossary/cloaking.md) — Serving materially different content to crawlers vs users — explicitly forbidden by Google.
- [Core Web Vitals](/glossary/core-web-vitals.md) — Google's headline page-experience metrics: LCP, INP, CLS.
- [Crawl budget](/glossary/crawl-budget.md) — The number of URLs a crawler is willing to fetch from your site within a given window.
- [Crawled, currently not indexed](/glossary/crawled-not-indexed.md) — A Search Console state: Google fetched the URL but decided not to add it to the index.
- [Cumulative Layout Shift (CLS)](/glossary/cls.md) — How much visible content unexpectedly shifts during a page lifetime.
- [Discovered, currently not crawled](/glossary/discovered-not-crawled.md) — A Search Console state: Google found the URL but has not yet fetched it.
- [Entity SEO](/glossary/entity-seo.md) — Optimizing for clear entity identification in search and answer engines.
- [GPTBot](/glossary/gptbot.md) — OpenAI's training crawler. Distinct from OAI-SearchBot.
- [hreflang](/glossary/hreflang.md) — A signal that tells search engines which language and region version of a page to serve.
- [Hydration](/glossary/hydration.md) — The process of attaching JavaScript event listeners to server-rendered HTML in the browser.
- [Incremental Static Regeneration (ISR)](/glossary/isr.md) — A hybrid where pages are static-served from cache but regenerated on demand or on a TTL.
- [Interaction to Next Paint (INP)](/glossary/inp.md) — Worst-case latency between a user input and the next visual update.
- [JSON-LD](/glossary/json-ld.md) — JSON-formatted structured data that Google and AI engines extract for entity understanding.
- [Largest Contentful Paint (LCP)](/glossary/lcp.md) — The render time of the largest content element visible in the viewport.
- [llms.txt](/glossary/llms-txt.md) — A proposed file at site root that hints to AI crawlers what content to prioritize.
- [OAI-SearchBot](/glossary/oai-searchbot.md) — OpenAI's search crawler. Indexes content for ChatGPT search-time grounding.
- [PerplexityBot](/glossary/perplexitybot.md) — Perplexity's crawler. Indexes content for Perplexity AI answer citations.
- [Prerendering](/glossary/prerendering.md) — Generating static HTML snapshots of JavaScript-rendered routes for crawlers and (sometimes) users.
- [RFC 9110 (HTTP Semantics)](/glossary/rfc-9110.md) — The current IETF standard defining HTTP semantics: methods, status codes, headers.
- [RFC 9309 (Robots Exclusion Protocol)](/glossary/rfc-9309.md) — The IETF standard that formally specifies robots.txt parsing and behavior.
- [robots.txt](/glossary/robots-txt.md) — A file at site root that tells crawlers which paths they may or may not fetch.
- [Server-Side Rendering (SSR)](/glossary/ssr.md) — Generating HTML on the server for every request, then sending it to the browser.
- [Soft 404](/glossary/soft-404.md) — A page that returns HTTP 200 but appears empty or 404-like to crawlers.
- [Static Site Generation (SSG)](/glossary/ssg.md) — Building every page as static HTML at build time and serving from a CDN.
- [Time to First Byte (TTFB)](/glossary/ttfb.md) — The time between request and the first byte of response from the origin or CDN.
- [Time to Interactive (TTI)](/glossary/tti.md) — The time until the main thread is reliably free to handle user input.
- [XML sitemap](/glossary/sitemap-xml.md) — An XML file listing the URLs you want crawlers to discover and prioritize.