link building guide

Link Building Glossary: 120+ SEO and Link Terms Explained

A plain-English link building glossary covering 120+ SEO and backlink terms, from anchor text and DR to PBNs, SpamBrain and AI Overviews.

Joe DaviesBy · Updated

This link building glossary explains the terms that come up when you build, buy, audit or measure backlinks, in plain English and in alphabetical order. Each definition is kept short, and where the site has a full guide on the topic, the entry links to it.

The terms cover the core vocabulary of links, the third-party metrics people use to judge them, the tactics, the Google concepts and policies that decide what is allowed, the technical SEO that affects how links are crawled, and the newer language of AI search. If you're starting from scratch, the start here page gives a reading order, and the core guides go deeper on each idea.

Numbers

301 redirect

A permanent redirect that sends visitors and search engines from one URL to another. Google's documentation says it treats a permanent redirect as a signal that the target URL should be the canonical one, which is why 301s are the standard way to keep the value of links pointing at a page you've moved.

302 redirect

A temporary redirect. Google follows it, but its documentation says a temporary redirect isn't treated as a signal that the target should be canonical, so it's the wrong choice when a move is permanent.

404 error

The status code a server returns when a page can't be found. Links pointing at 404 pages are the raw material of broken link building and link reclamation. More in our broken link building guide.

A

AI crawler

A bot run by an AI company that fetches web pages, either to train a model or to retrieve pages live when answering a question. Sites can allow or block most of them by name in robots.txt.

AI Mode

A Google Search feature that answers queries conversationally with an AI model, aimed at questions that need more exploration, reasoning or comparison. Google says there are no extra requirements or special optimisations needed to appear in it beyond normal SEO best practice.

AI Overviews

The AI-generated summaries shown at the top of some Google results, with links to the sources they draw on. Google's guidance says the same SEO fundamentals apply and no special markup is needed. More in our AI Overviews guide.

Alt text

The text description added to an image in its HTML. When an image is used as a link, Google's documentation says it uses the image's alt text as the anchor text.

Anchor text

The visible, clickable words in a link. Search engines use it as a hint about what the linked page is about, which is why over-optimised anchors are a classic sign of manipulation. More in our anchor text guide.

Anchor text ratio

The share of a site's backlinks that use each type of anchor (branded, naked URL, exact match and so on). Google has never published a safe ratio, so any target percentage is a rule of thumb taken from what ranks in a niche.

Authority Score

Semrush's 0 to 100 score for the overall quality of a domain, which blends link data with organic traffic and spam signals. Like DR and DA, it's a third-party estimate rather than a Google number.

B

A link from one website to another. Backlinks remain one of the signals Google uses to understand which pages are important and trustworthy. More in what backlinks are and why they matter.

A structured review of every link pointing at a site to find risky, broken or lost links and decide what to keep, fix or disavow. More in our backlink audit guide.

The full set of links pointing at a site, including how many there are, which domains they come from, the anchors used and how they were gained over time. Tools such as Ahrefs, Semrush and Majestic each build their own picture of it.

Link building that breaks search engine policies to manipulate rankings, such as PBNs, link farms and automated link spam. It can work briefly, but the risk of penalties and wasted spend is high. More in white hat vs black hat link building.

Blogger outreach

Contacting bloggers and site owners to earn a link, usually through a guest post, a mention or an added resource. More in our blogger outreach guide.

Branded anchor

Anchor text that uses a brand or company name, such as "Stridely" rather than "trail running shoes". Branded anchors usually make up the largest share of a natural profile.

Brand mention

Any reference to a brand on another website, whether or not it includes a link. Mentions matter more now that AI assistants draw on them when describing and recommending brands. More in brand mentions for AI visibility.

A link that points at a page which no longer exists or returns an error. Broken outbound links are a poor experience for readers, and broken inbound links waste value a site has already earned.

Finding dead pages that still have links pointing at them, creating a better replacement, and asking the linking sites to update their links to it. More in our broken link building guide.

Paying for a link placement, directly or through a vendor. Google's spam policies prohibit buying links that pass ranking credit, yet paid placements labelled with rel="sponsored" are allowed. More in is it safe to buy backlinks? and the buying and outsourcing guides.

C

Canonical tag

An HTML tag (rel="canonical") that tells search engines which version of a duplicated or near-duplicated page is the preferred one. Google treats it as a strong signal rather than a command, and links to the duplicates are generally consolidated into the canonical version.

A source that an AI system such as AI Overviews, ChatGPT or Perplexity names or links to in an answer. Being cited is the AI search equivalent of ranking. More in our LLM SEO guide.

Citation Flow (CF)

Majestic's 0 to 100 score that estimates how influential a URL or domain might be based on the volume of links pointing at it. It says nothing about quality on its own, which is why it's usually read alongside Trust Flow.

Cloaking

Showing search engines different content from what human visitors see, with the intent to manipulate rankings. Google's spam policies prohibit it.

Co-citation

When two sites or brands are mentioned together on the same page, even without a link between them. It's a widely discussed SEO concept for how search engines and AI systems associate entities, but Google hasn't documented how, or whether, it uses it.

A link placed inside the body text of an article, surrounded by relevant content, rather than in a sidebar, footer or author bio. It's the type most link buyers aim for. More in is it safe to buy backlinks?

Core update

A broad change to Google's main ranking systems, announced a few times a year. Rankings often shift during the rollout, and Google's advice is to focus on content quality rather than quick fixes.

Crawl budget

The number of URLs Google can and wants to crawl on a site, shaped by server capacity and how much demand there is for its pages. Google's guidance says it mostly matters for very large or fast-changing sites, roughly those with a million or more pages or 10,000 or more pages that change daily.

Crawling

The process of a search engine's bots fetching pages and following the links on them to find more. Links, both internal and external, are one of the main ways crawlers discover new URLs.

D

A link that points at an inner page of a site rather than the homepage. A healthy profile has plenty of them, because people link to the specific article or product they're referring to.

Digital PR

Creating newsworthy stories, data or campaigns and pitching them to journalists to earn coverage and links from news and media sites. More in our digital PR guide.

A link from a business or website directory listing. A small number of relevant, curated directories still help, but Google's spam policies name low-quality directory links as an example of link spam. More in our directory links guide.

Disavow

Telling Google to ignore specific links or domains by uploading a disavow file in Search Console. Google says most sites won't need to use the tool, which is meant for large numbers of spammy links that have caused, or are likely to cause, a manual action. More in our backlink audit guide.

Common shorthand for a normal link with no rel attribute that limits it, so it can pass ranking credit. There is no actual "dofollow" attribute in HTML. More in dofollow vs nofollow links.

Domain Authority (DA)

Moz's 1 to 100 score that predicts how likely a domain is to rank, based largely on its link profile. It's a Moz metric, not a Google one. More in Domain Rating vs Domain Authority.

Domain Rating (DR)

Ahrefs' 0 to 100 score for the strength of a website's backlink profile compared with the other sites in its database, on a logarithmic scale. It's an Ahrefs metric that Google doesn't use. Check any site with the free DR checker.

E

E-E-A-T

Experience, expertise, authoritativeness and trustworthiness, the qualities Google's quality guidance uses to describe helpful content. Google says trust is the most important of the four and that E-E-A-T isn't a specific ranking factor in itself.

A link from a site on a .edu domain, usually a US university or college. They're prized because they're hard to get, but Google hasn't said it gives a domain extension extra weight. More in our guide to .edu backlinks.

A link that a site owner or journalist chose to add because the content deserved it, without payment or a swap. It's the type of link Google's policies are designed to reward.

Entity

A distinct, identifiable thing, such as a brand, person, place or product, that search engines and AI systems can recognise and connect to facts. Consistent mentions across the web help a brand become a clearly understood entity.

Exact match anchor

Anchor text that matches the target keyword exactly, such as "trail running shoes" pointing at a trail running shoe page. It's the most powerful anchor type and the most likely to look unnatural when overused. More in our anchor text guide.

Expired domain

A domain whose registration lapsed and that's available to buy again, often with old backlinks still pointing at it. Google's spam policies prohibit buying an expired domain and repurposing it mainly to manipulate rankings with low-value content.

A link from one website to a different website. Seen from the receiving site it's a backlink, and seen from the linking site it's an outbound link.

F

A link placed in a site's footer, which usually appears on every page. Footer links are normal for navigation, but keyword-rich footer links bought across many sites are a familiar link scheme pattern.

Footprint

A shared pattern that reveals a group of sites or links were created by the same person or network, such as the same hosting, theme, owner details or writing style. Footprints are how PBNs and link farms tend to get spotted. More in our PBN guide.

A link posted in a forum thread or signature. Genuine contributions can send useful traffic, but Google's spam policies list forum comments with optimised links in the post or signature as link spam.

The basic set of profile, citation and brand links that most legitimate businesses pick up early, such as social profiles, business listings and partner pages. More in our foundational links guide.

G

Generative engine optimization (GEO)

The practice of improving how often and how well a brand or page appears in answers from AI systems such as ChatGPT, Perplexity and Google's AI features. It overlaps heavily with traditional SEO. More in our GEO guide.

Generic anchor

Anchor text that says nothing about the destination page, such as "click here", "this article" or "read more". Generic anchors are a normal part of a natural profile.

Google Search Console

Google's free tool for site owners, which shows search performance, indexing status, a sample of links Google knows about, and any manual actions against the site. It's also where the disavow tool lives.

Tactics that aren't automated spam but don't fit the purely earned definition either, such as paid guest posts and niche edits. Read strictly, Google's policies cover any link bought for ranking purposes that isn't marked sponsored or nofollow, so the risk depends on how it's done. More in white hat vs black hat link building.

Grounding

The process of an AI system basing its answer on retrieved sources, such as live search results or documents, rather than only on what the model learned in training. Grounded answers are the ones that cite and link to web pages.

Guest post

An article written for another website and published under the author's name, usually with a link back to the author's site. More in our guest posting guide.

Guest post marketplace

A platform where publishers list their sites with prices and buyers order guest posts or link placements directly. More in building links with a marketplace and the best link building marketplaces.

H

HARO

Help a Reporter Out, a service that matched journalists with expert sources and became shorthand for earning links by answering journalist requests. The original platform has changed hands and names in recent years. More in our HARO link building guide.

Helpful content

Google's term for content made primarily to help people rather than to rank. The helpful content system announced in 2022 became part of Google's core ranking systems in March 2024.

Hub page

A page that introduces a topic and links out to the detailed pages on it, which in turn link back. Hubs are a common way to organise internal links around a topic. More in our internal linking guide.

I

A link where the clickable element is an image rather than text. Its alt text plays the role that anchor text plays in a text link.

Another name for a backlink: a link pointing at a site from somewhere else.

Indexing

The step after crawling where a search engine stores and processes a page so it can appear in results. A page has to be indexed before any links on it can be counted.

A link from one page to another on the same site. Internal links help search engines find pages and spread authority from strong pages to the ones that need it. More in our internal linking guide.

J

Journalist requests

Queries from reporters looking for expert comment, sent through platforms or posted on social media. Answering them well can earn quotes and links on news sites. More in our HARO link building guide.

K

Keyword difficulty

A tool's estimate of how hard it will be to rank in the top results for a keyword. Ahrefs bases its version on how many referring domains the pages already ranking have, which makes it a rough guide to how many links you'll need. More in how many backlinks you need.

L

Content made specifically to attract links, such as original research, tools, calculators or striking data visuals. It's also called a linkable asset.

The work of getting other websites to link to yours, to improve rankings, referral traffic and visibility. More in the complete link building guide.

A company that plans and builds links for clients as a managed service, usually with outreach, content and reporting included. More in the best link building agencies.

A fixed bundle of links sold at a set price, often tiered by the authority of the sites. More in how much link building costs.

Any business that sells link building, from single guest posts to fully managed campaigns. More in the best link building services.

The ranking value a link is thought to pass from one page to another. It's the more formal name for link juice.

Two sites agreeing to link to each other. Occasional natural cross-links are fine, but Google's spam policies name excessive link exchanges as link spam. More in our link schemes guide.

A group of sites that exist mainly to link to each other or to paying customers, with little real content or audience. It's a long-standing form of link spam. More in our link schemes guide.

The difference between the sites linking to your competitors and the sites linking to you. Most backlink tools have a report for it, and it's a common starting point for prospecting.

Another name for a niche edit: adding a link to an article that's already published. More in our niche edits guide.

Informal SEO slang for the authority a link passes. It comes from the idea of PageRank flowing through links. More in what link juice is.

Recovering link value a site has lost or never collected, by fixing broken links to it or turning unlinked brand mentions into links. More in our link reclamation guide.

The gradual decay of links over time as pages are deleted, moved or redesigned. It's why a backlink count drifts down unless new links keep coming in.

Any arrangement to create links mainly to manipulate rankings, such as buying links that pass ranking credit, excessive swaps or automated link building. More in our link schemes guide.

Google's term for creating links to or from a site primarily to manipulate search rankings. Its spam policies list examples, and its SpamBrain system is used to detect and neutralise it.

The rate at which a site gains (or loses) links over time. Google hasn't published any "safe" speed, so advice about it is opinion, though sudden spikes of low-quality links are a common red flag. More in our link schemes guide.

LLM

Large language model, the type of AI system behind ChatGPT, Gemini, Claude and similar assistants. LLMs generate text from patterns learned in training, and many now also search the web to ground their answers.

LLM SEO

Optimising a brand and its content so that AI assistants mention, cite and recommend it. More in our LLM SEO guide.

llms.txt

A proposed standard, first published in September 2024, for a Markdown file at a site's root that gives AI systems a concise summary of the site and links to its key pages. It's a proposal rather than an official web standard, and publishing one doesn't guarantee any AI system will use it.

Local citation

An online mention of a business's name, address and phone number, usually on directories, maps and review sites. Consistent citations help local search visibility. More in our local citations guide.

Earning links from sites tied to a place, such as local news, councils, clubs, charities and business groups. More in link building for local businesses.

M

Manual action

A penalty applied when a human reviewer at Google decides that pages on a site don't comply with its spam policies. Search Console reports it, and the site can ask for a review once the problem is fixed. More in our backlink audit guide.

Media placement

A link or mention on a news or media site, earned through PR or paid for as sponsored content. More in our media placements guide.

Money page

The page a site most wants to rank because it makes money, such as a product, service or category page. Pushing too many keyword-anchored links straight at it is a common mistake.

N

Naked URL

Anchor text that is just the web address itself, such as "stridely.com". It's one of the most common anchor types in natural profiles.

Niche edit

A link added to an existing article on another site, usually one that's already indexed and has some authority. More in our niche edits guide.

Niche relevance

How closely the linking site's topic matches yours. A link from a relevant site in your industry is generally worth more, and looks more natural, than one from an unrelated site with higher metrics.

Nofollow

A rel attribute value that asks search engines not to associate the linking site with the destination. Since 2019 Google has treated nofollow as a hint rather than a strict rule. More in dofollow vs nofollow links.

Noindex

A directive that tells search engines not to show a page in results. It's set with a meta robots tag or an HTTP header, and it's different from blocking a page in robots.txt.

O

Off-page SEO

Everything done away from your own site to improve its rankings, with link building and brand mentions as the main parts.

On-page SEO

Optimising the content and HTML of a page itself, such as titles, headings, copy and internal links, so that search engines understand it and readers find it useful.

Orphan page

A page with no internal links pointing at it. Search engines may struggle to find it, and it gets none of the authority flowing around the site. More in our internal linking guide.

A link from your site to another site. Google's policies care about outbound links too: selling links that pass ranking credit can earn a manual action for unnatural links from your site.

Outreach

Contacting site owners, editors or journalists to ask for a link, a mention or a guest post opportunity. More in our outreach email templates.

Outsourcing

Paying an agency, freelancer or platform to handle link building instead of doing it in-house. More in outsourcing link building.

P

Page Authority (PA)

Moz's page-level score that predicts how likely a single page is to rank, on a 1 to 100 scale. It's the page equivalent of Domain Authority.

PageRank

Google's original link analysis algorithm, which treats a link as a kind of vote and weighs each vote by the importance of the page casting it. Google still describes using systems that understand how pages link to each other. More in what link juice is.

A link given in exchange for money, goods or services. Google's spam policies prohibit paid links that pass ranking credit, and expect them to carry rel="sponsored" or nofollow. More in our link schemes guide.

Partial match anchor

Anchor text that includes the target keyword alongside other words, such as "Stridely's guide to trail shoes". It carries relevance without looking as forced as an exact match.

PBN

Private blog network, a group of websites (often built on expired domains) controlled by one person and used to link to their own or clients' sites. It's a black hat tactic that breaks Google's spam policies. More in PBN backlinks and why to avoid them.

Penguin

The Google algorithm update launched in 2012 to target manipulative link building. It became part of Google's core algorithm in 2016. More in our link schemes guide.

Appearing as a guest on podcasts to earn links from show notes and episode pages. More in our podcast link building guide.

A link inside a press release, usually distributed through a wire service. Wire syndication alone rarely earns valuable links, and press release links with optimised anchors fall under Google's link scheme examples. More in our guide to press release links.

Prospecting

Finding and qualifying the sites worth approaching for a link, before any outreach starts. Good prospecting decides most of a campaign's results. More in link building tools.

Q

Query fan-out

A technique Google describes for AI Overviews and AI Mode, where the system runs several related searches across subtopics to build its answer. It means a page can be cited for questions it doesn't rank for directly. More in AI SEO and links.

R

RAG

Retrieval-augmented generation, an AI method where the system retrieves relevant documents first and then writes an answer based on them. It's the mechanism behind most AI answers that cite web pages.

A link given in return for a link back. A few are natural between genuine partners, but swapping links at scale is listed by Google as link spam. More in our link schemes guide.

Reconsideration request

The request a site owner submits in Search Console, after fixing the problem, to ask Google to review and lift a manual action. More in our backlink audit guide.

Redirect chain

A series of redirects where one URL redirects to another, which redirects again before reaching the final page. Pointing links and redirects straight at the final URL avoids wasted crawl requests and slower pages.

Referring domain

A unique website that links to yours, however many individual links it sends. Referring domains are usually a better measure of link strength than the raw backlink count. More in our referring domains guide.

Rel attribute

The part of a link's HTML that describes its relationship to the destination, such as rel="nofollow", rel="sponsored" or rel="ugc". More in dofollow vs nofollow links.

Resource page

A page that curates useful links on a topic for its readers. Resource page link building means finding these pages and suggesting your content as an addition. More in our resource page guide.

Robots.txt

A text file at a site's root that tells crawlers which URLs they may access. Blocking a page there stops it being crawled but doesn't reliably keep it out of the index, since Google can still find it through links.

S

Scaled content abuse

Google's term for generating many pages primarily to manipulate rankings rather than help users, whether by AI, automation or people. It's prohibited under its spam policies.

SERP

Search engine results page, the page of results shown for a query. It now often includes AI Overviews, featured snippets and other features alongside the classic links.

Site reputation abuse

Google's term for publishing third-party content on a host site mainly to exploit that host's ranking signals. It's prohibited under its spam policies and matters for anyone buying placements on large, unrelated sites.

Sitemap

A file, usually XML, that lists the URLs a site wants search engines to find. It helps with discovery but doesn't replace internal links, which also pass authority.

A link that appears on every page of a site, typically in the header, footer or sidebar. A single sitewide link can show up as thousands of backlinks from one referring domain.

Skyscraper technique

Finding popular content with lots of links, publishing a clearly better version, and asking the sites linking to the original to link to yours. More in our skyscraper technique guide.

Spam Score

Moz's metric for the percentage of sites with similar features that it has found to be penalised or banned by Google. A high score is a prompt to look closer, not proof of spam.

SpamBrain

Google's AI-based spam prevention system. Google has said it uses SpamBrain to detect and neutralise link spam, including in its December 2022 link spam update.

Paid content published on another site, usually including a link to the sponsor. Google expects links in sponsored content to carry rel="sponsored" or nofollow. More in our sponsored posts guide.

rel="sponsored"

The rel attribute value Google asks site owners to use on links that are advertisements or paid placements. It was introduced in 2019 and, like nofollow, is treated as a hint. More in our sponsored posts guide.

T

Building links to the pages that link to you (tier 2), and sometimes links to those (tier 3), to boost their strength. The lower tiers are usually low quality, which is where the risk sits. More in our tiered link building guide.

Topical authority

A widely used SEO term for how thoroughly a site is seen to cover a subject, built through in-depth content, internal links and relevant backlinks. Google doesn't publish a topical authority score.

Topical Trust Flow

Majestic's breakdown of Trust Flow by subject category, showing which topics a site's links come from. It's useful for checking niche relevance before getting a link.

A label some tools give to links they predict could harm a site. The scores are tool estimates, not Google's view, so they need human review before anything is disavowed. More in are toxic backlinks real?

Trust Flow (TF)

Majestic's 0 to 100 score for link quality, based on how closely a site is linked to a set of manually reviewed, trusted seed sites. It's usually compared with Citation Flow to spot sites with many links but little trust. More in link building tools.

U

rel="ugc"

The rel attribute value for links in user-generated content, such as comments and forum posts. Google introduced it in 2019 and treats it as a hint.

Unlinked mention

A mention of a brand, product or person that doesn't include a link. Asking the publisher to add one is often an easy win. More in our link reclamation guide.

URL Rating (UR)

Ahrefs' 0 to 100 score for the strength of a single page's backlink profile, on a logarithmic scale. It's the page-level partner to Domain Rating.

User-generated content links

Links added by visitors rather than the site owner, such as those in comments, forums and community profiles. Many platforms mark them nofollow or ugc automatically.

W

Links from pages created on free hosted platforms, such as blog hosts and profile sites. Created in bulk, they're a low-value tactic that falls under automated or low-quality link building. More in our foundational links guide.

Earning links in ways that follow Google's policies, such as creating useful content, digital PR and genuine outreach. More in white hat vs black hat link building.

Link building done by a provider and resold by an agency under its own brand, so the end client never sees the provider. More in our white label link building guide.

Y

YMYL

Your Money or Your Life, Google's label for topics that could significantly affect people's health, financial stability, safety or wellbeing. Google applies higher standards to these topics, which makes link quality and trust especially important in sectors such as healthcare and legal.

The short version

  • A backlink is a link from another site, and the number of unique referring domains usually matters more than the raw link count
  • DR and UR belong to Ahrefs, DA and PA to Moz, and Trust Flow and Citation Flow to Majestic, so none of them is a Google metric
  • Nofollow, sponsored and ugc are hints to Google, and paid links that pass ranking credit break its spam policies
  • Penguin, SpamBrain and manual actions are how Google has dealt with link spam, from algorithms to human review
  • AI search adds new terms such as GEO, grounding and citations, but links and brand mentions still feed into it

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