SEO Glossary: 100 Terms Explained
This glossary explains 100 terms you will meet when learning or doing SEO, from basics such as indexing and anchor text to newer ideas such as AI Overviews, generative engine optimisation and query fan-out. Definitions are short and practical, and they follow Google's own documentation where Google defines a term. Terms are grouped alphabetically, so you can scan a section or use your browser's find function to jump to a word.
How to use this glossary
- Find the term. Scan the alphabetical sections or use Ctrl+F (Cmd+F on Mac) to search the page.
- Read the definition in context. Note related terms mentioned in the definition and look those up too.
- Go deeper with the guides. Follow the linked SEO guides for full explanations and worked examples.
A–C
- AEO (answer engine optimisation)
- Optimising content so it is selected as the direct answer to a question, for example in featured snippets, voice assistants or AI answers. It relies on clear questions, concise answers and well-structured pages.
- AI Mode
- A Google Search experience where an AI model answers complex questions conversationally, using query fan-out to search many subtopics and linking to supporting web pages.
- AI Overviews
- AI-generated summaries that Google shows at the top of some search results, with links to the web pages used as sources. Pages need to be indexed and eligible for a snippet to be shown as a link.
- Alt text
- The
altattribute on an image, describing it for screen-reader users and search engines. It also helps images appear in image search. - Anchor text
- The visible, clickable text of a link. Descriptive anchor text helps users and search engines understand what the linked page is about.
- Backlink
- A link from another website to yours. Links from relevant, trusted sites help search engines discover pages and judge their importance.
- Black-hat SEO
- Tactics that break search engine spam policies, such as cloaking, link schemes or hidden text. They risk manual actions or loss of rankings.
- Breadcrumb
- A navigation trail showing where a page sits in the site hierarchy, for example Home > SEO > Technical SEO. It can be marked up with BreadcrumbList schema.
- Canonical URL
- The preferred URL among a set of duplicate or very similar pages. You can suggest it with
rel="canonical", redirects and sitemaps, but Google makes the final choice. - ccTLD
- A country-code top-level domain such as .in or .uk. Google treats it as a strong signal that a site targets that country.
- Click-through rate (CTR)
- Clicks divided by impressions. In Search Console it shows how often people who saw your result clicked it.
- Cloaking
- Showing search engines different content from what users see. It breaks Google's spam policies.
- Core update
- A broad change to Google's core ranking systems, made several times a year. Pages can rise or fall without having done anything wrong.
- Core Web Vitals
- Google's three user-experience metrics: LCP for loading, INP for responsiveness and CLS for visual stability. They are measured from real Chrome users at the 75th percentile.
- Crawl budget
- The number of URLs a search engine can and wants to crawl on a site in a given time. It mainly matters for very large or frequently updated sites.
- Crawler
- A program, also called a bot or spider, that fetches web pages by following links and sitemaps. Googlebot is Google's main crawler.
- Crawling
- The process of a search engine bot discovering and downloading pages. A page must usually be crawled before it can be indexed.
- Cumulative Layout Shift (CLS)
- A Core Web Vital measuring unexpected movement of page content while it loads. A score of 0.1 or less is considered good.
D–F
- Disavow
- A Search Console tool for asking Google to ignore specific links to your site. Google advises using it only if you have a manual action or know of many spammy, artificial links you cannot remove.
- Domain Authority
- A third-party score from Moz estimating how strong a domain's backlink profile is. Similar metrics include Ahrefs Domain Rating. Google does not use them.
- Duplicate content
- Identical or very similar content available at more than one URL. It is usually not penalised, but it splits signals and wastes crawling until a canonical is chosen.
- E-E-A-T
- Experience, expertise, authoritativeness and trustworthiness: a framework from Google's Search Quality Rater Guidelines for judging content quality. Trust is described as the most important part.
- Entity
- A distinct, well-defined thing such as a person, place, organisation or concept. Search engines connect entities in knowledge graphs to understand meaning beyond keywords.
- External link
- A link from your site to a page on another domain. Citing reliable sources helps readers verify information.
- Faceted navigation
- Filters on category pages, such as size or colour, that create many URL combinations. Without control, it can produce huge numbers of low-value URLs.
- Featured snippet
- A highlighted result that shows an extract from a page answering the query directly, above or near the top of the organic results.
- First Input Delay (FID)
- A former Core Web Vital for responsiveness. INP replaced it in March 2024.
G–I
- GEO (generative engine optimisation)
- Optimising content and brand presence so it is retrieved and cited by AI-generated answers, such as AI Overviews, ChatGPT or Perplexity. It builds on SEO basics with clear, extractable content and wider brand mentions.
- Google Analytics 4 (GA4)
- Google's current analytics platform, based on events. Conversions are called key events.
- Google Business Profile
- A free listing that controls how a business appears in Google Maps and the local pack, including address, hours, photos and reviews.
- Google Search Console
- Google's free tool for site owners, showing search performance, indexing status, Core Web Vitals, manual actions and more.
- Googlebot
- Google's web crawler. It mainly crawls as a smartphone user agent because Google uses mobile-first indexing.
- Heading tags
- HTML elements from
<h1>to<h6>that structure content into sections. Clear headings help readers and search engines follow a page. - Helpful content
- Content created mainly to help people rather than to rank. Google's separate helpful content system was folded into its core ranking systems in March 2024.
- hreflang
- An attribute that tells search engines which language or regional version of a page to show to which users, for example
en-infor English in India. - HTTPS
- The secure version of HTTP, encrypting data between the browser and server. Google uses HTTPS as a lightweight ranking signal.
- Impressions
- In Search Console, the number of times a URL from your site appeared in search results that a user saw or could have seen.
- Indexing
- The stage where a search engine processes a crawled page, renders it, chooses a canonical and stores it in the index.
- IndexNow
- A protocol that lets sites notify participating search engines, such as Bing and Yandex, when URLs change. Google does not use it.
- Interaction to Next Paint (INP)
- A Core Web Vital measuring how quickly a page responds visually to clicks, taps and key presses across the visit. 200 milliseconds or less is good.
- Internal link
- A link from one page to another on the same site. Internal links help discovery, show hierarchy and pass link value.
J–L
- JavaScript SEO
- Making sure content and links generated by JavaScript can be crawled, rendered and indexed. Server-side rendering usually reduces risk.
- JSON-LD
- JavaScript Object Notation for Linked Data: the structured data format Google recommends, added in a script block rather than mixed into the HTML.
- Keyword
- A word or phrase people type or speak into a search engine. In practice, SEO targets topics and intents that groups of keywords share.
- Keyword cannibalisation
- When several pages on one site target the same query and compete with each other, so none performs as well as one strong page would.
- Keyword difficulty
- A third-party estimate of how hard it is to rank for a keyword, usually based on the backlinks of current top results. Each tool calculates it differently.
- Keyword research
- Finding the words and questions your audience uses, along with their intent and relative demand, to decide what content to create.
- Knowledge Graph
- Google's database of entities and the relationships between them, used to understand queries and show facts.
- Knowledge panel
- An information box in Google results about an entity, such as an organisation or person, drawn from the Knowledge Graph.
- Largest Contentful Paint (LCP)
- A Core Web Vital measuring when the largest image or text block in the viewport is displayed. 2.5 seconds or less is good.
- Link building
- Activities that earn links from other websites, such as creating linkable resources, digital PR and partnerships. Buying links for ranking breaks Google's spam policies.
- llms.txt
- A proposed plain-text file that gives AI tools a summary of a site's key content. It is not an official standard, and Google has said its AI features do not need it.
- Local pack
- The map and list of nearby businesses Google shows for searches with local intent, drawn from Google Business Profiles.
- Log file analysis
- Studying server access logs to see exactly which URLs search engine bots request, how often and with what response codes.
- Long-tail keyword
- A longer, more specific search phrase with lower individual demand, such as "technical seo course pune weekend batch". Together they make up a large share of searches.
M–O
- Manual action
- A penalty applied by a human reviewer at Google when a site breaks spam policies. It is shown in Search Console and can be appealed with a reconsideration request after fixing the issue.
- Meta description
- An HTML tag summarising a page. Google may use it as the snippet in results, but it is not a ranking factor.
- Meta robots tag
- An HTML tag giving crawlers page-level instructions such as
noindexornofollow. - Mobile-first indexing
- Google's practice of using the mobile version of a page, crawled with smartphone Googlebot, for indexing and ranking.
- NAP
- Name, address and phone number. Keeping NAP consistent across a website, Google Business Profile and directories supports local SEO.
- Nofollow
- A link attribute,
rel="nofollow", telling search engines not to associate your site with the linked page. Google treats it as a hint. - Noindex
- A directive in a meta robots tag or X-Robots-Tag header that tells search engines not to show a page in results. The page must be crawlable for the directive to be seen.
- Off-page SEO
- Work outside your own site that builds reputation and visibility, such as earning links, mentions and reviews.
- On-page SEO
- Optimising elements on a page itself, such as content, title, headings, internal links and images, for users and search engines.
- Orphan page
- A page with no internal links pointing to it. Search engines may struggle to find it and treat it as unimportant.
P–R
- PageRank
- Google's original algorithm for judging a page's importance from the links pointing to it. It is still one of many signals Google uses, though no longer shown publicly.
- Pagination
- Splitting a long list of content across numbered pages. Each page should be crawlable through normal links and have its own canonical.
- People also ask
- A Google results feature showing related questions that expand to reveal short answers from web pages.
- Pillar page
- A broad page covering a main topic and linking to more detailed cluster pages on subtopics, which link back to it.
- Programmatic SEO
- Creating many pages from templates and a dataset, for example one page per city or product. Each page still needs unique, useful content to avoid being thin or spammy.
- Query fan-out
- A technique used in Google AI Mode and similar AI search tools: the system splits a question into many related sub-queries, searches them at the same time and combines the results into one answer.
- Ranking
- The position of a page in search results for a query, decided by many signals about relevance, quality and usability.
- Redirect
- Sending users and bots from one URL to another. 301 and 308 are permanent; 302 and 307 are temporary.
- Redirect chain
- A series of redirects from one URL to another and then another. Chains slow users down and waste crawling; redirect straight to the final URL.
- Rendering
- Running a page's HTML, CSS and JavaScript to build what users see. Google renders pages with an up-to-date version of Chromium.
- Rich results
- Search results with extra visual features, such as review stars, prices or event dates, often enabled by structured data.
- robots.txt
- A text file at the root of a host that tells crawlers which URLs they may or may not crawl. It controls crawling, not indexing.
S–T
- Schema.org
- A shared vocabulary of types and properties, such as Article and Product, used to write structured data. It is supported by Google, Bing and other search engines.
- Search intent
- The goal behind a search, often grouped as informational, navigational, commercial or transactional. Matching intent is essential for ranking.
- Search Quality Rater Guidelines
- Google's published guidelines for human raters who evaluate search results. Ratings help Google test changes; they do not directly change any site's rankings.
- SERP
- Search engine results page: the page shown after a search, including organic results, ads and features.
- SERP features
- Elements on a results page beyond standard links, such as AI Overviews, featured snippets, People also ask, local packs, images and videos.
- Site migration
- A major change to a site, such as a new domain, URL structure, CMS or move to HTTPS, that needs careful redirects and monitoring to keep traffic.
- Soft 404
- A page that tells users it does not exist, or has almost no content, but returns a 200 status code instead of 404 or 410.
- Spam policies
- Google's rules describing practices that can cause a site to rank lower or be removed, such as cloaking, link spam, scaled content abuse and site reputation abuse.
- Structured data
- Code that describes a page's content in a standard format, usually JSON-LD using schema.org, so search engines can understand it and show rich results.
- Technical SEO
- Improving a site's infrastructure so it can be crawled, rendered and indexed efficiently: robots.txt, sitemaps, redirects, speed, HTTPS and more.
- Thin content
- Pages with little original or useful content, such as near-empty tag pages or auto-generated text.
- Title link
- Google's name for the clickable headline of a search result. It is usually based on the title tag but can be generated from headings or other text.
- Title tag
- The HTML
<title>element naming a page. It is one of the strongest on-page signals of what the page is about. - Topic cluster
- A group of related pages on one subject, interlinked around a pillar page, that together cover the topic in depth.
- Topical authority
- An informal term for a site being seen as a reliable, comprehensive source on a subject because it covers the topic broadly and deeply.
U–Z
- URL Inspection tool
- A Search Console tool showing whether a URL is indexed, which canonical Google chose and how Googlebot rendered it. You can also request indexing.
- URL parameter
- Part of a URL after a
?, such as?sort=price. Parameters can create duplicate URLs for the same content. - User agent
- The name a browser or bot sends to identify itself, such as Googlebot. robots.txt rules can target specific user agents.
- User-generated content (UGC)
- Content created by users, such as comments, reviews and forum posts. Links in it should use
rel="ugc"or nofollow. - X-Robots-Tag
- An HTTP response header that carries robots directives such as noindex. It is useful for non-HTML files such as PDFs.
- XML sitemap
- A file listing the URLs you want search engines to know about, optionally with last-modified dates. Each file can hold up to 50,000 URLs or 50 MB uncompressed.
- YMYL
- Your money or your life: topics that could significantly affect people's health, finances, safety or wellbeing. Google holds them to higher quality standards.
- Zero-click search
- A search that ends without a click to any website, because the answer was shown on the results page itself, for example in an AI Overview or featured snippet.
Frequently asked questions
Which SEO terms should a beginner learn first?
Start with crawling, indexing, ranking, search intent, keyword, title tag, internal link, backlink and Search Console. Most other terms build on these.
What is the difference between SEO, GEO and AEO?
SEO covers visibility in search engines generally. AEO focuses on being the direct answer to a question, and GEO on being cited in AI-generated answers. They share the same foundations: crawlable pages, clear content and trusted sources.
Are third-party metrics such as Domain Authority used by Google?
No. Metrics such as Domain Authority or Domain Rating are calculated by SEO tool companies to estimate link strength. They can be useful for comparison, but Google does not use them.
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