SEO Wiki
Short definitions are useful. But when you're fixing rankings, you usually need the details. This wiki expands our glossary into practical, example-driven notes.
A2A Agent Card
An A2A Agent Card is a discovery document that describes an agent's identity, capabilities, endpoint, authentication, and skills.
Agent Commerce Signals: x402, ACP, UCP, AP2 and MPP
Agent commerce signals are protocols and metadata patterns that help AI agents discover products, authenticate, pay, and complete transactions safely.
Agent Skills Index
An agent skills index is a machine-readable list of what a website or service can do for AI agents, from search and checkout to support and audit workflows.
API Catalog SEO
API Catalog SEO makes public APIs discoverable to search engines and AI agents through OpenAPI, documentation, links, and metadata.
Auth.md and OAuth Metadata
Auth.md and OAuth metadata help AI agents understand authentication, authorization servers, protected resources, scopes, and consent boundaries.
DNS-AID: DNS Discovery for AI Agents
DNS-AID is an emerging shorthand for using DNS records as a discovery signal for AI agents, usually through TXT records and metadata endpoints.
Link Headers for AI Agents
Link headers are HTTP response fields that help AI agents discover machine-readable resources such as sitemaps, llms.txt, API catalogs, and policies.
MCP Server Card
An MCP server card is an agent-readable summary of an MCP server's tools, resources, authentication requirements, and safe usage boundaries.
WebMCP
WebMCP is an emerging idea for browser-native tool discovery, where websites expose agent-callable capabilities through metadata or MCP endpoints.
AEO (Answer Engine Optimization): how to be cited by AI answers
Learn what Answer Engine Optimization is, how it differs from SEO, and what signals make your content get cited in AI answers.
Agentic search: when AI agents do the searching for you
Agentic search is the shift from single-query search to AI agents that plan, search, read, and act on your behalf across many tools and sources.
AI Brand Mentions: the new currency of generative search
AI brand mentions—being named in answers from ChatGPT, Perplexity, and AI Overviews—are now a measurable ranking and trust signal. Track and grow them.
AI citations: how to be the source in AI answers
AI citations are the inline links and attributions that answer engines add to the sources they use. Earning them is the new goal of generative SEO.
AI Crawlers: GPTBot, ClaudeBot, PerplexityBot and more
AI crawlers are bots operated by LLM providers to discover and index pages for training or retrieval. Decide which to allow and which to block.
AI Overviews: how Google's AI answers work and how to rank in them
AI Overviews are Google's AI-generated answer boxes that appear above traditional results. Learn how they work and what it takes to be cited in them.
AI referral traffic: measuring visits from ChatGPT, Perplexity, Gemini
AI referral traffic is the visits your site receives when users click a citation in ChatGPT, Perplexity, Gemini, or another AI answer. Measure and grow it.
Brand SERP: what Google shows when people search your brand
Your brand SERP is the search result page Google shows for your own brand name. It is a key trust and conversion surface you can shape.
ChatGPT Search: optimizing for OpenAI's search experience
ChatGPT Search is OpenAI's search experience inside ChatGPT, blending live web results with the assistant's conversational answers.
Citation rate: the core metric of AI-era SEO
Citation rate measures how often a domain is cited in AI-generated answers for a defined topic set. It is the most direct measure of AEO success.
ClaudeBot: Anthropic's web crawler
ClaudeBot is Anthropic's web crawler, used to keep Claude's knowledge current and to power citations in its answers.
Conversational search: from keywords to dialogue
Conversational search treats each query as part of an ongoing dialogue, with context carried across turns. It rewards content that is structured to answer follow-ups.
Core Web Vitals: LCP, INP, CLS and the modern UX ranking signal
Core Web Vitals are Google's user-experience metrics—LCP, INP, and CLS—measuring loading, interactivity, and visual stability.
DeepSeek: the open-weights AI challenger in search
DeepSeek is an open-weights AI company whose models power a fast-growing search and chat product. It is a notable new surface in AI search.
Digital PR: earning coverage, links, and AI mentions
Digital PR earns brand mentions, authoritative links, and—increasingly—AI citations by getting your story into publications that matter.
E-E-A-T: Experience, Expertise, Authoritativeness, Trustworthiness
Understand Google's E-E-A-T framework, what each signal means, and how to demonstrate it on your content to win in modern search.
Embeddings: the math behind semantic search
Embeddings are dense numerical vectors that represent the meaning of text, images, or other data. They are the foundation of semantic search and RAG.
Entity SEO: optimizing for the Knowledge Graph
Entity SEO is the practice of associating your brand, products, and content with disambiguated entities in Google's Knowledge Graph to win richer placements.
GEO (Generative Engine Optimization): optimizing for AI search
Generative Engine Optimization (GEO) is the practice of optimizing content to be cited and surfaced by generative AI search experiences.
GPTBot: OpenAI's web crawler explained
GPTBot is OpenAI's web crawler. It can be used both to train future models and to surface content in ChatGPT search. Decide how to handle it.
Helpful Content Update: what changed and how to recover
Google's Helpful Content Update targets content made for search engines rather than people. Understand the signals and how to align your site.
Hreflang: serving the right language and region
Use hreflang to tell search engines which language and region a page targets. Avoid common mistakes that break multilingual SEO.
Information Gain: adding new value to a topic
Information gain is the unique, additive value your content brings to a topic. Google explicitly rewards pages that contribute something the SERP does not already have.
Knowledge Graph: how Google organizes what it knows
The Knowledge Graph is Google's structured database of entities and their relationships. It powers knowledge panels, entity cards, and rich results.
Knowledge panel: how to earn and control it
A knowledge panel is the boxed information shown on the right of Google results for entities like brands, people, and places. Earn and shape it.
LLM hallucination: why AI sometimes makes things up
LLM hallucination is when a language model produces confident but false information. For SEO, it shapes how answer engines pick and trust sources.
LLM Optimization: optimizing for large language models
LLM Optimization is the discipline of making your content easy for large language models to retrieve, understand, and cite. It overlaps heavily with AEO and GEO.
llms.txt: the proposed standard for AI crawlers
llms.txt is a proposed file that gives LLM-driven crawlers a clean, machine-readable summary of your site—analogous to robots.txt for the AI era.
MCP: the Model Context Protocol for AI agents
The Model Context Protocol (MCP) is an open standard that lets AI agents connect to tools, data sources, and apps in a consistent, secure way.
Multimodal search: text, image, audio, and video together
Multimodal search lets users combine text, image, audio, and video in a single query. It is changing how content is discovered and ranked.
Natural Language Processing (NLP) in SEO
NLP helps search engines understand meaning, entities, and intent. Learn how it shapes modern SEO and how to write for it.
Negative SEO: what it is and how to defend your site
Negative SEO is the practice of attacking a competitor's rankings. Recognize common tactics and protect your site with practical defenses.
Nofollow links: what they do and when to use them
A nofollow link tells search engines not to pass ranking signals. Learn when nofollow is the right choice and how Google treats it today.
Off-page SEO: signals beyond your site
Off-page SEO includes backlinks, brand mentions, and entity associations. Learn what matters and what to ignore.
On-page SEO: optimizing the page itself
On-page SEO covers everything you control on a page: titles, headings, content, internal links, and structured data.
Organic search: the foundation of long-term traffic
Organic search drives the most consistent, compounding traffic. Learn how it works and what it takes to win placements.
PAA (People Also Ask): how to win related questions
The People Also Ask box is a high-visibility SERP feature. Learn how it works and how to structure content to appear in it.
Page speed: faster pages rank better and convert more
Page speed affects rankings, bounce rate, and revenue. Learn the metrics Google uses and the fixes that actually move the needle.
Pagination SEO: handling paginated content correctly
Pagination is how you split long content across pages. Implement it correctly with rel=next/prev, view-all, and canonical signals.
Parasite SEO: borrowing authority from big platforms
Parasite SEO is the practice of publishing content on high-authority third-party platforms to piggyback on their rankings. Risky, but still widely used.
Passage indexing: ranking passages, not just pages
Passage indexing lets Google rank individual passages within a page. It changes the unit of optimization from page to paragraph.
Perplexity AI: the answer engine reshaping search
Perplexity AI is a conversational answer engine that synthesizes answers from live web sources with inline citations. It is one of the main surfaces to optimize for in 2026.
PerplexityBot: how Perplexity crawls the web
PerplexityBot is Perplexity's web crawler. Unlike many AI bots, its main purpose is to surface content in live answers, not to train models.
Position zero: the SERP feature above position one
Position zero refers to the SERP feature that appears above the first organic result—featured snippets, AI Overviews, PAA, and more.
Prompt engineering: writing prompts that get reliable answers
Prompt engineering is the practice of crafting inputs that steer large language models toward accurate, useful, and safe outputs. It is a core SEO-adjacent skill.
Quality Score: what it is and how Google uses it
Quality Score estimates ad relevance and landing page experience. While it lives in Ads, the same signals improve organic SEO too.
Query decomposition: how AI breaks complex questions into parts
Query decomposition is the AI-era technique of splitting a complex question into several sub-queries, answering each, then synthesizing a final answer.
Query understanding: how search engines read your query
Query understanding is the process search engines use to interpret intent, entities, and context behind a query. Writing for it changes how your content ranks.
Search query: the foundation of SEO
A search query is what a user types into a search engine. Understanding query intent is the starting point for any SEO strategy.
Question-based keywords: capturing question intent
Question keywords start with who, what, where, when, why, or how. Match them with structured answers to win PAA and featured snippets.
Ranking factors: the signals that move the SERP
Ranking factors are the signals search engines use to order results. Learn the ones that matter and how to weigh them.
Rich snippets: enhanced listings that get more clicks
Rich snippets add stars, prices, FAQs, and more to your listing. Implement them with structured data to lift CTR and visibility.
Robots.txt: controlling what crawlers can access
Robots.txt is a file that tells crawlers which paths they may request. Use it carefully—a wrong rule can deindex your site.
Schema markup: structured data for richer results
Schema markup is structured data that helps search engines understand your content. Use it to unlock rich results and knowledge panels.
Search Everywhere Optimization: winning beyond Google
Search Everywhere Optimization is the practice of optimizing for every surface where people search—Google, YouTube, TikTok, Amazon, ChatGPT, Perplexity, and beyond.
SGE: Google's Search Generative Experience explained
Search Generative Experience (SGE) is Google's generative AI surface inside Search. Learn how it changes the SERP and what to do about it.
Semantic SEO: optimizing for meaning, not just keywords
Semantic SEO focuses on covering topics, entities, and intent—not just target keywords. It is the foundation of modern, AI-era search visibility.
SERP: understanding the search results page
The SERP is the page that shows search results. Modern SERPs include featured snippets, PAA, image packs, and AI overviews.
Share of Model: measuring visibility in AI answers
Share of Model is a metric that measures how often your brand appears in AI-generated answers for a given topic set, similar to Share of Voice for traditional search.
Site reputation abuse: Google's policy on parasite SEO
Site reputation abuse is Google's policy against hosting third-party content on authoritative domains purely to ride their rankings—also called parasite SEO.
Source-of-truth content: the basis for AI citations
Source-of-truth content is structured, authoritative content that AI engines repeatedly cite. It is the new foundation of brand visibility in AI answers.
SSL certificate: HTTPS, trust, and ranking
An SSL certificate enables HTTPS, which is a confirmed Google ranking signal and a baseline trust signal for users.
Structured Data: schema, JSON-LD, and machine-readable SEO
Structured Data is standardized markup that helps search engines and AI systems understand the meaning of your pages, not just their words.
Technical SEO: the foundation that everything else builds on
Technical SEO covers crawling, indexing, rendering, site speed, and structured data. Get it right and the rest of SEO gets easier.
Thin content: low-value pages that hurt your site
Thin content is low-value, shallow, or auto-generated content. Identify and improve or remove it to lift overall site quality.
Title tag: the most important on-page ranking factor
The title tag is the clickable headline in search results. Write one that matches intent, includes the topic, and fits the pixel limit.
Topic clusters: the pillar-cluster model for SEO
A topic cluster is a pillar page supported by a group of interlinked articles on subtopics. It is the classic way to build topical authority.
Topical authority: how to become the source for a topic
Topical authority is the perception—shared by users and search engines—that your site is the definitive source on a given subject. Build it with depth and structure.
URL structure: clean, readable, and stable
A clean URL structure helps users and search engines. Use short, descriptive slugs and avoid parameter soup.
User experience (UX): the signals behind modern SEO
User experience drives engagement, conversions, and rankings. Learn the Core Web Vitals and UX signals Google measures.
User intent: the why behind every search
User intent is the goal behind a query: informational, navigational, commercial, or transactional. Match it to rank and convert.
Vector search: how AI finds similar meaning
Vector search retrieves documents by similarity in a mathematical embedding space, not by exact keyword match. It powers modern RAG and AI answer engines.
Vertical search: specialized engines for specific content
Vertical search engines focus on a specific content type: images, video, news, shopping, or local. Optimize for the ones your audience uses.
Visual search: ranking with images and cameras
Visual search lets users search with images instead of text. Optimize images with alt text, structured data, and high-quality visuals.
Voice search: optimizing for spoken queries
Voice search queries are longer, more conversational, and question-based. Optimize for natural language and direct answers.
Web crawler: how search engines discover pages
A web crawler is a bot that discovers and indexes web pages. Understand how it works to make your site easy to crawl.
Web standards: consistent, accessible, future-proof
Web standards are the official guidelines (HTML, CSS, accessibility) that keep the web consistent. Following them is good SEO and good citizenship.
White hat SEO: techniques that follow the rules
White hat SEO follows search engine guidelines and focuses on users. It builds durable rankings without the risk of penalties.
X-Robots-Tag: controlling indexing at the HTTP level
The X-Robots-Tag HTTP header controls indexing and snippetting without HTML. Use it for non-HTML files and edge-case crawling rules.
XHTML: HTML with XML's strict syntax
XHTML is HTML written in XML syntax. Strict, but largely replaced by HTML5. Learn when it still matters and when to use HTML5 instead.
XML sitemap: helping crawlers find your pages
An XML sitemap lists the URLs you want crawled. Submit it in Search Console to help search engines discover and prioritize your content.
Yahoo Search: powered by Bing, with its own audience
Yahoo Search is powered by Microsoft Bing. Most SEO work transfers, but Yahoo has its own portal audience worth considering.
Yandex: Russia's leading search engine
Yandex is Russia's largest search engine. It has its own ranking factors and behaviors; localize your strategy if you target Russian users.
YMYL: pages that affect health, money, or safety
YMYL pages can impact a person's wellbeing, so Google holds them to a higher E-E-A-T standard. Identify yours and raise the quality bar.
Zero-click search: answering queries without a click
A zero-click search is one where the user gets the answer on the SERP. Win them with structured data, PAA, and direct, scannable answers.
Zero-result SERP: when Google answers without listings
A zero-result SERP shows no organic results. Google provides a direct answer for queries it can answer with high confidence.
Zone file: the DNS map of a domain
A zone file lists the DNS records for a domain. It is the source of truth for how a domain name resolves to services on the web.
AEO (Answer Engine Optimization): How to rank for direct answers
AEO is the practice of optimizing content to appear as direct answers in search engines, featured snippets, voice search, and AI chatbots.
GEO (Generative Engine Optimization): How to rank in AI-powered search
GEO is the practice of optimizing content to appear in AI-generated search responses from Google SGE, ChatGPT, Perplexity, and other generative engines.
Image Optimization: How to speed up your site without losing quality
Image optimization reduces file size while preserving visual quality. Learn compression formats, responsive images, lazy loading, and Core Web Vitals impact.
Junk Content: What it is, why it hurts SEO, and how to clean it up
Junk content is low-value text that bloats pages and confuses search engines. Learn how to identify, remove, and prevent it without losing useful information.
Link Building: A practical guide to earning quality backlinks in 2026
Link building remains a core ranking factor. Learn proven strategies for earning quality backlinks, avoiding toxic links, and measuring link profile health.
Local SEO: How to rank your business in local search results
Local SEO helps businesses appear in local search results and Google Maps. Learn GBP optimization, citation building, and local ranking factors.
Long-tail Keywords: Why specific phrases convert better than broad terms
Long-tail keywords are longer, more specific search phrases with lower competition and higher conversion rates. Learn how to find and target them effectively.
Meta Description: How to write snippets that earn clicks
Meta descriptions don't directly affect rankings but heavily influence click-through rates. Learn how to write compelling, accurate descriptions that convert.
Meta Tags: The complete guide to HTML metadata for SEO
Meta tags provide search engines with information about your pages. Learn which tags matter, which don't, and how to implement them correctly.
Mobile-First Indexing: Why your mobile site is your ranking site
Google uses the mobile version of your site for indexing and ranking. Learn how to ensure your mobile experience delivers equal content, structured data, and metadata.
Query Fan-out: How AI Search Expands Your Content's Reach
Learn how Google's query fan-out technique works in AI search and what it means for your content strategy and SEO optimization.
RAG (Retrieval-Augmented Generation): How AI Search Finds and Uses Your Content
Learn how Retrieval-Augmented Generation works in Google Search and why it matters for your content's visibility in AI-powered search results.
Scaled Content Abuse: Google's Spam Policy on Mass-Produced Content
Learn what scaled content abuse is, how Google detects it, and how to avoid violating this critical spam policy in your SEO strategy.
AI SEO: The Future of Search Engine Optimization
Discover how artificial intelligence is transforming SEO and learn strategies to leverage AI tools for better search rankings and content optimization.
E-E-A-T: Experience, Expertise, Authority, Trustworthiness in SEO
E-E-A-T is Google's updated framework for evaluating content quality. Learn how to demonstrate experience, expertise, authority, and trustworthiness to improve your rankings.
Engagement Rate: How User Interaction Affects SEO
Engagement rate measures how users interact with your content. Learn how metrics like bounce rate, time on page, and click-through rate impact your SEO.
External Link: How Outbound Links Impact SEO
External links are hyperlinks that point to other websites. Learn how outbound links can improve your SEO, establish authority, and enhance user experience.
Featured Snippet: How to Rank in Google's Position Zero
Featured snippets are the highlighted answers that appear at the top of Google search results. Learn how to optimize your content to earn this highly visible position.
Footer: How to Optimize Your Website Footer for SEO
Your website footer is more than just a place for copyright information. Learn how to optimize your footer for SEO, user experience, and conversion.
Freshness: How Content Freshness Impacts SEO
Freshness is a ranking factor that considers how recent your content is. Learn how to optimize your content for freshness and when it matters most.
Gateway Page: What They Are and Why They're Bad for SEO
Gateway pages are low-quality pages created solely for search engines. Learn why they're considered spam and how to avoid penalties.
Geo Targeting: How to Optimize Your Website for Local SEO
Geo targeting helps you reach users in specific locations. Learn how to optimize your website for local search and improve your local SEO rankings.
LLM Search Optimization: Optimizing for Large Language Model Search
Learn how to optimize your content for large language model search and generative AI platforms to improve visibility in AI-powered search results.
Multilingual SEO: Optimizing for Global Audiences
Learn how to optimize your website for multiple languages and regions, reaching global audiences while maintaining strong search rankings.
Dofollow link: what it means (and why it's a misleading term)
Dofollow isn't an official attribute. Learn how link equity works, what nofollow really does today, and how to audit your links.
Duplicate content: what it is, why it happens, and how to fix it
Duplicate content confuses indexing and can split ranking signals. Learn common duplicate patterns and practical fixes using canonical, redirects, and internal linking.
Domain Authority: what it is (Moz), what it isn't (Google), and how to use it
Domain Authority (DA) is a Moz metric, not a Google ranking factor. Learn how to interpret DA/DR-style scores without fooling yourself.
CTR (click-through rate): what it measures and how to improve it safely
CTR is the percentage of impressions that become clicks. Learn what affects CTR in Google Search and how to improve titles, snippets, and intent match.
Crawling: how search engines discover pages (and what blocks them)
Crawling is how bots discover your pages. Learn crawl paths, crawl budget basics, and common blockers like robots.txt, noindex, and soft 404s.
Breadcrumbs in SEO: navigation, UX, and structured data
Breadcrumbs help users and crawlers understand site structure. Learn when to use breadcrumbs, how to mark them up, and common implementation mistakes.
Bounce rate: what it means, what it doesn't, and how to interpret it in SEO
Bounce rate is often misunderstood. Learn when it signals a real problem, when it's normal, and how to diagnose the underlying UX issues.
Backlink: what it is, what makes it valuable, and what makes it risky
Backlinks still matter, but not all links are equal. Learn what makes a backlink helpful, how anchor text plays in, and red flags to avoid.
Anchor text: how link text influences SEO (and how to avoid over-optimization)
Anchor text is the clickable text in a link. Learn practical anchor text patterns for internal and external links, plus common mistakes.
Search algorithm: what it means in SEO (and what it doesn't)
In SEO, an algorithm is the system that decides what ranks. Learn how to think about algorithms, signals, and updates without chasing myths.
Googlebot: how the search crawler works (and how to work with it)
Learn how Googlebot crawls sites, what limits and priorities it uses, and how to check crawl issues without guesswork.
Heading tags (H1-H6): how to use them for structure, not tricks
Learn how headings work for accessibility and SEO, what not to do, and how to audit heading structure on any page.
HTTP status codes: what 200, 301, 404, and 500 mean for SEO
Understand the status codes that matter most for crawlability, indexing, and user experience.
Indexing: how Google stores (and uses) your pages
Learn the difference between crawling and indexing, what stops indexing, and how to check index coverage.
Internal links: how they help crawlability and discovery
Internal links connect your pages to each other. Learn how to use them wisely for better crawl depth and user flow.
JavaScript SEO: making sure Google renders your content
Learn how Google renders JavaScript, what breaks indexing, and how to test if your JS content is visible.
JSON-LD: structured data for rich results and understanding
Learn how JSON-LD works, what schema types to use, and how to test your structured data.
Keyword density: why percentages don't matter, but natural writing does
Learn what keyword density is, why old rules about percentages are bad advice, and how to write naturally without stuffing.
Keyword stuffing: what it is, why it backfires, and how to avoid it
Keyword stuffing used to work. Now it hurts your site. Learn how to spot it and write naturally instead.
Keywords: how searchers talk, and how to match intent
Keywords are the bridge between your content and what searchers are looking for. Learn how to think about them without obsessing.
Alt text: what it is, why it matters, and how to write it
Alt text helps search engines and screen readers understand images. Learn how to write useful, non-spammy alt text with examples and quick audits.