SEO glossary: 51 terms explained in plain language.
The words you hear in SEO, explained simply, with links to free tools and guides when you want to go further.
The basics
SEO (search engine optimization)
The work of making a website easier for search engines to find, understand and trust, so it can appear for the searches your customers make.
Organic traffic
Visits that come from unpaid search results, as opposed to ads.
SERP
Search engine results page: the page of results you see after a search.
Ranking (position)
Where a page appears in the results for a search. Position 1 is the top organic result. Rankings differ by location, device and person. See how to check your ranking.
Keyword (search query)
The words someone types or says into a search engine. People use many different words for the same need.
Search intent
The reason behind a search: to learn something, find a site, compare options or buy. A page ranks better when it matches the intent.
Impressions, clicks and CTR
An impression is when your page appears in results. A click is a visit from them. CTR (click-through rate) is clicks divided by impressions.
Crawling
When a search engine's bot, such as Googlebot, follows links to discover and read pages.
Indexing
When a search engine stores a page so it can be shown in results. A page that is crawled is not always indexed.
Technical SEO
XML sitemap
A file that lists the pages you want search engines to find. It helps discovery but does not guarantee indexing. Check yours with our Sitemap Validator.
robots.txt
A text file at the root of your site that asks crawlers which areas not to crawl. It is not a security tool. Create one with our Robots.txt Generator.
Canonical tag
A tag that tells search engines which version of similar pages is the main one.
Noindex
An instruction that asks search engines not to show a page in results. The page must be crawlable for the instruction to be seen.
301 redirect
A permanent redirect from one URL to another. Use it when a page has moved for good.
302 redirect
A temporary redirect. Use it when the original address will come back.
Redirect chain
A URL that redirects to another redirect, and so on. It slows pages down. Find chains with our Redirect Checker, or read how to fix them.
404 error
The answer a server gives when a page cannot be found. A few are normal. Fix broken links on important pages with our Broken Link Checker.
HTTPS
The secure version of HTTP, which encrypts traffic between the visitor and the site. Google has described it as a lightweight ranking signal.
Core Web Vitals
Google's measures of page experience: LCP (how fast the main content loads), INP (how quickly the page responds to taps and clicks) and CLS (how much the layout jumps around).
Page speed
How quickly a page loads and becomes usable. Check yours with our Site Speed Tester.
Mobile-friendly
A page that is easy to read and use on a phone. Google mostly uses the mobile version of a page for indexing and ranking.
Structured data (schema markup)
Code that describes a page's content to search engines in a standard format, usually JSON-LD. Create it with our Schema Markup Generator.
hreflang
A tag that tells search engines which language or region each version of a page is meant for.
Crawl budget
The number of URLs a search engine will crawl on your site in a given time. Google says it mainly matters for very large sites.
On-page SEO
Title tag
The headline of a page in search results. Keep it clear and specific. Check yours with our Title Tag Checker.
Meta description
A short summary of a page that search engines may show under the title. Google says it does not use it for ranking, but it can affect clicks. See meta tags that matter.
Heading tags (H1 to H6)
Headings that give a page structure. The H1 is the main heading, and most pages should have one.
Alt text
A short description of an image, used by screen readers and search engines.
Internal link
A link from one page of your site to another. Internal links help visitors and crawlers move around and show which pages matter.
Anchor text
The clickable words of a link. Descriptive anchor text tells people and search engines what the linked page is about.
URL slug
The readable last part of a URL, such as /seo-glossary/. Keep it short and clear.
Thin content
Pages with little or no useful content for visitors.
Duplicate content
Content that appears on more than one page or site. Use canonical tags and redirects to show which version is the main one.
Keyword stuffing
Repeating a word or phrase unnaturally to try to rank. Google's spam policies list it as a violation. See our Keyword Density Checker.
E-E-A-T
Experience, Expertise, Authoritativeness and Trustworthiness: ideas in Google's quality guidelines for judging content. They are not a single ranking score.
Links and authority
Backlink
A link to your site from another site. Links from relevant, trusted sites are a strong signal.
Link building
The work of earning links from other sites, for example with useful tools, guides and data. Read how we do it on our link building page.
Nofollow
A link attribute (rel nofollow, sponsored or ugc) that tells search engines not to treat the link as a vote of trust.
Domain Authority
A score created by Moz that predicts how well a site might rank. Google does not use it, so treat it as a rough guide only.
Broken link
A link that leads to a page that does not exist. Find them with our Broken Link Checker, or read how to fix them.
Local SEO
Google Business Profile
Your free listing on Google Search and Maps, with your name, address, hours, services and reviews.
Local pack
The map and short list of businesses that appears for many local searches.
NAP
Name, address and phone number. Keep them identical everywhere online.
Citation
A mention of your business details on another website, such as a directory.
AI search and analytics
AI Overviews
AI-written summaries that Google shows at the top of some results, with links to sources. See how to get cited.
GEO and AEO
Generative engine optimization and answer engine optimization: making your content easy for AI tools and answer boxes to understand and cite. Read GEO vs AEO.
Featured snippet
A highlighted answer box at the top of some results, taken from a page.
Google Search Console
Google's free tool that shows how your site appears in search, including clicks, impressions, indexing problems and sitemaps.
UTM parameters
Tags added to a link so analytics shows where a visit came from. Build them with our UTM Link Builder.
Conversion
A visitor doing something valuable, such as calling, filling in a form or buying.
Open Graph tags
Tags that control how a link looks when it is shared on social networks. Create them with our Meta Tag Generator.
Put the terms to work.
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