SEO glossary

47 terms our reports use, in plain English. Written for someone who runs a business, not for someone who does SEO — if a definition here needs a second definition to make sense, it is not finished.

What does SEO stand for?

Search Engine Optimisation

It is the work of making a website easier for search engines to read, and more likely to be shown when somebody searches for what you sell. Two halves: the technical one, which is whether Google can reach your pages, understand them and trust them, and the editorial one, which is whether what they say is worth showing. Nobody can buy a ranking, and nobody outside Google can see how the ranking is decided — so SEO is removing the reasons not to show you, and then giving it something worth showing.

Fundamentals

Term	What it means
Algorithmic Penalty	A negative drop in rankings automatically triggered by a search engine's algorithm when a website violates quality guidelines.
Keyword	A word or phrase that a person types into a search box when looking for information.
Search Console	Google's own free tool for site owners. It is the only place you can see what Google actually did with your site — which pages it indexed, which searches you appeared for, and what it could not crawl. No third-party tool has that data, including this one, and anything claiming to show you your Google impressions without connecting to it is estimating.
Search Engine	Software (like Google or Bing) that reads websites worldwide and decides which ones to display when someone searches for something.
Search Intent	The underlying reason why a person conducts a specific search (e.g., to buy something, find a specific website, or learn information).
SERP	Search Engine Results Page. The page of results you see after typing a query into a search engine.

Discovery & Access

Term	What it means
Crawl Budget	The limited number of pages a search engine software will visit on your website during a single session before leaving.
Crawl Depth	How many clicks it takes to reach a page from the home page. Not a ranking factor by itself, but a page five or six clicks deep is reached rarely and re-checked rarely, and on a large site may not be reached at all. If a page matters, link to it from somewhere that matters.
Crawling	The process where search-engine software visits your pages by following links, much like a person clicking around your website.
Indexing	The step after crawling where a search engine decides whether to save your page in its database for future searches. A page that is crawled but not indexed will never appear in search results.
JavaScript Rendering	Building the page in the browser after the server has sent it. Google does render JavaScript, but in a second pass and on its own schedule, so anything that only appears after the script runs is seen later and sometimes not at all. The practical test is what the server sends before any script runs — if the title, the headings and the main text are not in that, you are relying on a second visit you do not control.
noindex	An instruction telling search engines not to list a page in search results. Useful on purpose, but disastrous by accident.
Orphan Page	A page with no links pointing to it from anywhere else on your site — like a room with no door. It exists, but visitors and search engines can rarely find it.
robots.txt	A plain text file at the root of a site that tells crawlers which addresses they may fetch. It controls crawling, not listing: a page blocked here can still appear in search results if other sites link to it, because Google can learn the address exists without ever fetching it — it simply has nothing to show underneath. To keep a page out of search, let it be crawled and use noindex instead.
XML Sitemap	A digital table of contents that lists every page you want found, helping search engines discover pages buried deep or poorly linked.

On-Page SEO

Term	What it means
Alt Text	A written description of an image for search engines and visually impaired users. It is a key accessibility requirement and the main way images get found in image search.
Breadcrumb	The trail near the top of a page showing where it sits — Home / Guides / This page. It helps visitors, and with the right structured data Google will show the trail in search results in place of the bare address, which is easier to read and reassures somebody before they click.
H1 Heading	The main headline at the top of a page, like a newspaper headline. It tells both readers and search engines what the page is about. Every page should have exactly one.
Internal Link	A hyperlink that connects one page on your website to another page on the same website, helping users and search engines navigate your content.
Keyword Cannibalisation	Two or more of your own pages competing for the same search, so neither is clearly the best answer and both rank worse than one good page would. Usually the result of writing a second article on a subject you already covered. The fix is to merge them and redirect the weaker address, not to delete it.
Meta Description	The short summary paragraph under the blue link in search results. Like the blurb on the back of a book, it doesn't change your rank, but it convinces people to click.
Open Graph	A set of tags that decide how your page looks when somebody shares it on social media or in a chat app — the headline, the description and the picture in the preview card. They do nothing for Google rankings. They do decide whether a shared link looks like something worth clicking, which is why a missing one quietly costs traffic that never shows up as an SEO problem.
Thin Content	A page with very little helpful text or information. While not automatically penalized, pages with almost nothing to say rarely earn good rankings.
Title Tag	The digital name of your page. It appears as the blue clickable line in Google results and the text in your browser tab — think of it as the sign above a shop.

Technical SEO

Term	What it means
404 Error	A message showing that a web address does not exist — a dead end for visitors and a wasted trip for search engines.
Canonical Tag	A note saying 'this is the original version of this page'. If the same content exists at multiple web addresses, this tells search engines which one to display so they don't compete with each other.
Duplicate Content	The same or near-same text reachable at more than one address — most often the printer-friendly version, the same product under two categories, or the site answering on both www and non-www. There is no penalty for it, whatever you have been told: Google picks one address to show and ignores the rest. The cost is that it may not pick the one you wanted, and any links pointing at the others are split between them. A canonical tag is how you tell it which to pick.
hreflang	Digital signposts for multilingual sites that tell search engines exactly which language or regional version of a page to show to specific readers.
HTTP Status Code	The three-digit number a server answers with before it sends the page. 200 means here it is; 301 means it has moved for good; 302 means it has moved for now; 404 means there is nothing here; 410 means there was something here and it is gone deliberately; 500 means the server broke; 503 means come back later. Search engines treat each one differently, which is why returning the wrong one quietly costs traffic.
Mixed Content	A secure page (https) that loads an image, stylesheet or script over the insecure one (http). Browsers block or warn about it, so the page can look broken to a visitor while appearing fine to you. Usually left behind after a site moves to https and some address in the template was never updated.
Redirect	Mail forwarding for web pages. When a page moves, a redirect automatically sends visitors and search engines to the new address.
Redirect Chain	An inefficient setup where a page is forwarded multiple times (Page A to B, then B to C). This slows down loading speeds and leaks search engine value.
Server Response Time	How long your website takes to answer when someone knocks. Slow answers cause visitors to leave before the page even loads.
Soft 404	A confusing error where a page tells the search engine 'everything is fine' while actually displaying a blank page or a 'not found' message — like an empty shop with its 'Open' sign lit.
Structured Data (Schema)	Hidden labels on your page that spell out what things mean in a language computers understand (e.g., 'this is a price'). This enables star ratings and extra details to appear in search results.

Off-Page SEO

Term	What it means
Anchor Text	The visible, clickable words in a hyperlink. It gives search engines a clue about the topic of the page being linked to.
Backlink	A link from someone else's website to yours. It acts as a vote of confidence and is one of the strongest signals used to determine your search ranking.
Domain Authority	A score (created by third-party tools) that predicts how well a website will rank on search engines based on its overall link strength.
Nofollow	An attribute on a link that tells search engines you do not vouch for where it points. It is the right thing on paid links, on anything a user posted, and in comments. Since 2019 Google treats it as a hint rather than an order. It does not stop a page being found: if anything else links there, it will be.

User Experience

Term	What it means
Core Web Vitals	Google's official metrics that measure how a page feels to use: how fast the main content loads, how quickly it responds to user interaction, and whether elements jump around unexpectedly.
Cumulative Layout Shift	CLS: how much the page jumps about while it loads. Google counts 0.1 or less as good. It is the reason you tap the wrong button when an advert or an image loads late and pushes everything down. The common fix is unglamorous: give every image a width and a height so the browser can reserve the space before the file arrives.
Interaction to Next Paint	INP: when somebody taps or clicks, how long before the page visibly responds. Google counts 200 milliseconds or less as good. It replaced First Input Delay in March 2024 and is stricter, because it measures every interaction rather than only the first one.
Largest Contentful Paint	LCP: how long until the biggest thing on screen — usually the main image or headline — has actually appeared. Google counts 2.5 seconds or less as good. It is the closest single number to what a visitor means by the site feeling fast, and the usual culprits are a large unoptimised image and scripts in the head that stop the page being built.
Mobile Viewport	A setting that tells mobile devices how to scale your page to fit smaller screens. Without it, mobile visitors see a desktop page shrunk to an unreadable size.
Mobile-First Indexing	Google reads the phone version of your site, not the desktop one, and ranks on what it finds there. It has worked this way for every site since 2023. If your phone version hides content, loads fewer products or drops the structured data, that lesser version is the one being judged.

Future Search

Term	What it means
AI Overviews	The AI-written summary at the top of many Google searches. It answers questions directly, meaning fewer people click through to websites. Being cited inside this summary is increasingly critical.

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