Every SEO term you need, defined in plain language — from anchor text to query fan-out. Bookmark this glossary and check definitions here instead of guessing. Every term links to the free tool that demonstrates it in practice.
The glossary
Anchor text
The clickable words in a hyperlink. Search engines read anchor text as a description of the linked page, so natural, varied anchors matter more than keyword-stuffed ones.
Canonical tag
A rel="canonical" link element that declares the preferred version of a page when similar URLs exist, consolidating ranking signals onto one URL.
Crawl budget
The number of pages a search engine crawler is willing to fetch from your site in a given period. Large sites with many low-value URLs waste it.
Crawl depth
How many clicks a page sits from the homepage. Deep pages are crawled less often and accumulate less internal link equity.
Domain Authority
Moz's comparative metric (0-100) estimating ranking strength based on link profile. Useful for comparisons, not an official Google metric.
Domain Rating
Ahrefs' comparative metric estimating the strength of a website's backlink profile on a 0-100 scale.
E-E-A-T
Experience, Expertise, Authoritativeness and Trust — Google's quality framework, most strictly applied to pages about money, health, and safety topics.
Featured snippet
A selected search result displayed above the organic listings that answers the query directly. Also called position zero.
Hreflang
An annotation that tells search engines which language and regional version of a page to show users in different locations.
Indexability
Whether a page is eligible to appear in search results after crawling. Controlled by noindex tags, robots.txt, and canonical signals.
INP
Interaction to Next Paint — Google's metric for page responsiveness, measuring how quickly the page responds after a user interaction. Replaced FID in 2024.
Internal link
A hyperlink from one page on your site to another page on the same site. The primary tool for concentrating link equity on important pages.
Keyword clustering
Grouping keywords with the same search intent onto a single page, so one page ranks for a family of related queries instead of several pages competing.
Keyword stuffing
Repeating a target phrase unnaturally to manipulate rankings. A spam signal that triggers demotions rather than improvements.
LCP
Largest Contentful Paint — the Core Web Vital measuring loading performance, specifically when the largest visible element finishes rendering.
CLS
Cumulative Layout Shift — the Core Web Vital measuring visual stability, or how much page content jumps around during loading.
Link equity
The ranking value passed from one page to another through hyperlinks, historically called link juice.
Long-tail keyword
A specific, longer search phrase with lower volume and lower competition than a head term. Easier for newer sites to rank for.
Meta description
An HTML tag summarizing a page for search results. Not a direct ranking factor, but strongly affects click-through rate when Google displays it.
Nofollow
A rel attribute (rel="nofollow") telling search engines not to pass ranking credit through a link. Common on user-generated content.
Noindex
A robots meta tag directive preventing a page from appearing in search results even when it is crawled.
Organic results
Search results that are not paid ads, ranked by Google's algorithms rather than auction position.
Orphan page
A page on your site that no other page on your site links to, reachable only through the sitemap or external links.
Robots.txt
A text file at the domain root telling crawlers which URLs they may fetch. Controls crawling, not indexing.
Schema markup
Structured data (usually JSON-LD) that describes page content in machine-readable form, enabling rich results and AI citations.
Search intent
The goal behind a search query: informational, navigational, commercial, or transactional. Pages must match intent to rank.
SERP
Search Engine Results Page — the page of results returned for a query, including organic listings, ads, and features like snippets.
Snippet
The title, URL, and description Google displays for a page in search results. Drafted from your title tag and meta description.
Sitemap
An XML file listing the URLs you want crawled, usually with lastmod dates. Referenced in robots.txt and submitted via Search Console.
301 redirect
A permanent redirect passing essentially all link equity to the new URL. The correct redirect for permanent URL changes.
302 redirect
A temporary redirect. Using it for permanent moves delays the transfer of ranking signals.
Title tag
The HTML element that becomes the clickable headline of a search result. The strongest on-page element you fully control.
URL slug
The human-readable portion of a URL after the domain, ideally short, lowercase, and hyphen-separated.
Canonical conflict
When a page's canonical tag disagrees with its redirects or sitemap, sending contradictory signals to search engines.
Content decay
The gradual loss of traffic and rankings as content ages, competitors publish fresher material, and search demand shifts.
Cannibalization
When multiple pages on one site compete for the same keyword, splitting signals so neither page ranks as well as it could.
Disavow
A file submitted to Google asking it to ignore specific backlinks. Only needed for large-scale manipulative link patterns.
Impressions
The count of times your page appeared in search results, whether or not it was clicked. Available in Search Console.
Click-through rate
The percentage of impressions that become clicks. Low CTR at a page-one position signals a weak title or snippet.
Pillar page
A comprehensive page covering a broad topic, linked from narrower cluster pages that go deep on subtopics.
Topic cluster
A content architecture where a pillar page and its supporting subtopic pages interlink around one subject.
Programmatic SEO
Creating many pages from templates filled with data or combinations. Powerful at scale, risky when pages lack genuine usefulness.
LLMs.txt
A proposed standard file at the domain root listing key pages and guidance for large language model crawlers. A hint, not a standard.
Core Web Vitals
Google's three page-experience metrics: LCP (loading), INP (responsiveness), and CLS (visual stability).
Crawled – not indexed
A Search Console status meaning Google fetched the page but chose not to index it — usually a quality or duplication signal.
Duplicate content
Substantially identical content appearing at multiple URLs. Consolidate with canonicals or redirects rather than hoping Google picks one.
Pagination
Splitting content across multiple URLs (page=2, etc.). Each paginated page needs unique value or careful canonical handling.
Referring domain
A unique website linking to you. Counting domains matters more than counting individual links.
Toxic backlink
A manipulative link attempting to harm or artificially inflate rankings. Disavow only at clear, large-scale patterns.
Manual action
A demotion applied by a human Google reviewer for guideline violations. Visible in Search Console under Security and Manual Actions.
Algorithm update
A change to Google's ranking systems, rolled out continuously and in named core updates, causing visibility shifts across affected sites.
Search visibility
The share of impressions your site earns across tracked keywords relative to total available impressions.
Text-to-HTML ratio
The amount of visible text relative to HTML code on a page. A crude quality signal used by some audit tools.
Render-blocking resource
CSS or JavaScript files that delay page painting until they finish loading, hurting LCP.
Lazy loading
Deferring offscreen image and component loading until the user scrolls near them. Helps speed, hurts discovery if overused.
Alt text
The HTML attribute describing an image for screen readers and image search. Missing alt text fails accessibility and image SEO checks.
Open Graph tags
Meta tags (og:title, og:description, og:image) controlling how a page looks when shared on Facebook, LinkedIn, and messaging apps.
Structured data
Any machine-readable description of page content. Schema.org vocabularies expressed as JSON-LD are the search-engine-recommended format.
Rich result
An enhanced search result with extra elements like FAQ dropdowns, review stars, or breadcrumbs, earned by valid schema markup.
Position zero
The featured snippet slot above the first organic result. Winning it can double click-through rate for informational queries.
Search demand
The volume of searches a keyword receives over a period, typically estimated monthly.
Keyword difficulty
An estimate of how hard it will be to rank on page one for a keyword, based on the strength of currently ranking pages.
Seed keyword
The starting phrase you expand from during keyword research, usually your core product or topic.
Intent mismatch
When a page's content type does not match the intent behind the keyword it targets — the most common reason good content fails to rank.
Faceted navigation
Filtered, sorted, or layered URLs in ecommerce and directories. A major source of crawl-waste and duplicate content when uncontrolled.
Trailing slash
The final / in a URL. Two versions of the same page with and without it are duplicate URLs unless canonicalized.
Subdomain
A prefix-based subset of a domain (blog.example.com). Links and authority to subdomains do not fully transfer to the main domain.
Crawler
An automated program that fetches web pages. Googlebot is Google's; GPTBot and ClaudeBot serve AI assistants.
Index
Google's database of pages it has chosen to store and serve in results. Crawling is fetching; indexing is storing.
Ranking factor
A signal Google uses to order results. Hundreds exist; backlinks, relevance, and page experience are among the strongest confirmed.
Search equity
The cumulative ranking value a page or domain has earned through links, content quality, and user signals.
Evergreen content
Content that stays relevant for years with occasional updates, as opposed to news or trend pieces that decay fast.
Content pruning
Removing, consolidating, or noindexing low-value pages so crawl budget and internal links concentrate on pages that earn traffic.
Redirect chain
A sequence of redirects (A → B → C) that slows users, wastes crawl budget, and dilutes ranking signals.
Hreflang reciprocity
The requirement that hreflang annotations work in both directions: if page A points to page B, page B must point back to page A.
Log file analysis
Studying server logs to see exactly which crawlers visit which URLs and how often — the ground truth of crawl behavior.
Crawl depth distribution
The spread of pages across click depths. A healthy site concentrates important pages at depth 1-3.
Internal search results
Site search URLs (/?s=query). Usually blocked from indexing because they create near-infinite thin duplicate pages.
WWW versus non-www
Two hostname versions of one domain. Pick one, 301 the other, and keep the canonical consistent everywhere.
HTTP to HTTPS migration
Moving a site to encrypted connections. Requires 301 redirects for every URL and an updated canonical and sitemap.
Page experience
Google's umbrella for usability signals: Core Web Vitals, mobile-friendliness, HTTPS, and absence of intrusive interstitials.
Dwell time
How long a searcher stays on your page before returning to results. A user-behavior signal correlated with satisfaction.
Pogo-sticking
When a searcher clicks a result and immediately returns to the SERP to click another — a strong negative satisfaction signal.
Query refinement
When users modify a search to get better results, signaling the original results — including yours — failed to satisfy intent.
Entity
A distinct, unambiguous thing search engines understand: a person, brand, product, or concept. Entity SEO focuses on making entities clear.
Topical authority
Google's assessment of how comprehensively a site covers a subject, built through clustered, interlinked content rather than single pages.
Linkable asset
Content specifically built to earn backlinks: original research, free tools, data studies, and definitive guides.
Digital PR
Earning coverage and links through newsworthy content, data, and outreach rather than paid link placement.
Skyscraper technique
Finding content with many backlinks, creating a significantly better version, then asking the linking sites to update.
Broken link building
Finding broken links on relevant sites and offering your page as a replacement destination.
Unlinked mention
A brand mention without a hyperlink. Easy win: ask the author to add a link to your site.
Link gap
The set of domains linking to your competitors but not to you — the highest-priority outreach prospect list.
Anchor text distribution
The mix of branded, naked-URL, exact-match, and generic anchors in your backlink profile. Over-optimized exact match looks manipulative.
Nofollow ratio
The share of your backlinks carrying rel="nofollow". A natural profile mixes followed and nofollowed links.
Disavow file
A text file of domains or URLs you ask Google to ignore, uploaded via Search Console. Use rarely and carefully.
Crawl delay
An instruction asking crawlers to wait between requests. Respected by some crawlers, ignored by Googlebot.
Rate limiting
Restricting how many requests a server serves per time window. Misconfigured limits can block Googlebot accidentally.
robots meta tag
An HTML meta element (index/noindex, follow/nofollow) controlling indexing and link following for a single page.
X-Robots-Tag
An HTTP header version of the robots meta tag, applying noindex to any resource type including PDFs and images.
Canonical conflict
When a page's canonical, robots directives, and sitemap send contradictory signals about the preferred URL.
Sitemap coverage
The match between URLs in your sitemap and URLs Google has actually indexed. Gaps reveal discovery or quality problems.
Index bloat
Too many low-value indexed pages diluting site quality signals and wasting crawl budget. Common after programmatic launches.
Thin content
Pages with little unique value — doorway pages, auto-generated combinations, or shallow stubs. A demotion risk at site scale.
Doorway page
A page built primarily to rank for one query and funnel users elsewhere, with little standalone value. Against Google guidelines.
Interstitial
A full-screen overlay shown before or during page view. Intrusive mobile interstitials are a page-experience negative.
Progressive rendering
Serving content in stages as resources load. Better than pure client-side rendering for crawlability.
Hydration
The process of making server-rendered HTML interactive with JavaScript. Heavy hydration costs can hurt INP.
SSG
Static Site Generation — pre-rendering pages at build time. Fast and crawlable, requiring rebuilds for content changes.
ISR
Incremental Static Regeneration — updating static pages after deployment without full rebuilds. Balances speed and freshness.
TTFB
Time to First Byte — how long the server takes to send the first response byte. The upstream of LCP performance.
Critical CSS
The minimum CSS needed to render above-the-fold content, inlined to unblock rendering while other styles load deferred.
Resource hints
DNS prefetch, preconnect, preload, and prefetch directives that warm up connection and asset loading before the browser needs them.
CDN
Content Delivery Network — servers distributed geographically that cache and serve static assets closer to users, improving TTFB.
Compression
Gzip or Brotli encoding of HTML, CSS, and JavaScript responses, typically cutting transfer sizes by 60-80 percent.
Cache headers
HTTP directives (Cache-Control, ETag) controlling how long browsers and CDNs may store copies of a response.
HSTS
HTTP Strict Transport Security — a header forcing browsers to use HTTPS only, preventing protocol downgrade attacks.
Content security policy
A header (CSP) restricting which script and resource origins a browser may execute, reducing XSS risk.
CORS
Cross-Origin Resource Sharing — headers controlling how resources may be requested from other domains.
Pagination crawl trap
Infinite or deep pagination loops that waste crawl budget on low-value pages. Fix with canonicals or noindex on deep pages.
Faceted crawl trap
Uncontrolled filter combinations in ecommerce creating millions of thin URLs. Control with robots, canonicals, or parameter handling.
Parameter handling
Deciding which URL query parameters change content (keep) and which are decorative (consolidate or ignore).
UTM parameter
Tracking tags appended to URLs (utm_source, utm_medium). Harmful in indexed URLs — keep them out of canonicals and sitemaps.
Backlink profile
The complete set of external links pointing to a site, including volume, quality, anchor mix, and follow attributes.
Link velocity
The rate at which a site gains new backlinks. Sudden spikes from irrelevant sources resemble manipulation.
Negative SEO
Malicious attempts to harm a competitor's rankings, typically through spammy link attacks or content scraping. Rarely effective at scale.
Penguin
Google's algorithm targeting manipulative link patterns. Modern versions run in real time as part of the core system.
Helpful content system
Google's classifier demoting content written primarily for search engines rather than people. Site-wide effect when triggered.
Scaled content abuse
Google spam policy targeting large volumes of auto-generated or templated content with little added value.
Site reputation abuse
Publishing third-party or sponsored content on a trusted domain primarily to borrow its ranking signals.
Expired domain abuse
Registering a previously authoritative domain and repurposing it with unrelated low-quality content.
Extraneous SERP manipulation
Faking usage data, reviews, or clicks to influence rankings. A policy violation when deceptive.
AI Overview
Google's AI-generated answer displayed above organic results for some queries, citing sources with links.
Answer engine
AI systems (ChatGPT, Perplexity, Claude) that respond to questions with synthesized answers and source citations.
Citation share
The frequency with which your pages appear as cited sources in AI answers for your topic's queries.
Retrieval
The step where an answer engine fetches candidate documents before generating its response. Accessibility and structure decide retrieval.
Grounding
Tying an AI answer to specific retrieved sources. Pages that state facts cleanly are easier to ground.
Passage ranking
Google's ability to rank a specific passage of a page for a query even when the whole page targets a broader topic.
Multitask Unified Model
Google's MUM technology understanding text, images, and soon video across languages for complex query understanding.
BERT
Google's language model improving understanding of word context in queries, especially prepositions and conversational phrasing.
RankBrain
Google's machine-learning system helping interpret novel queries it has not seen before.
Navboost
Google's system using click data from search results as a ranking signal, per antitrust trial disclosures.
Query fan-out
Google expanding a short query into multiple related sub-queries to gather comprehensive results — raising the bar for page completeness.
Free tools to see these concepts in action
- SEO quick audit — most on-page terms above appear as audit checks
- Backlink checker — see referring domains, anchor text, and follow attributes live
- Structured data validator — validate the schema markup terms in this glossary
Frequently asked questions
How should I use this glossary?
Look up any term you hit in an audit report or article, then open the linked tool to see the concept on a real page. Definitions are updated as terminology evolves.
Are these official definitions?
They explain how each concept works in practice and how Google describes it, written for site owners rather than academics. Where Google has changed a definition (like INP replacing FID), the glossary reflects the current version.
Will you add more terms?
Yes. This glossary is updated quarterly alongside our audit studies as new systems — especially AI search terminology — evolve.
