Link Building and SEO Glossary: 40 Terms Defined

A link building glossary is a reference list of the terms SEO teams use to plan, buy, measure and audit backlinks. This page defines 40 terms in 5 groups: link basics, link types, metrics, process and outreach, and risk and policy.

Every definition opens with a direct answer. Metric entries name their source: Domain Rating and URL Rating come from Ahrefs, and Domain Authority comes from Moz. Policy entries follow Google's spam policies and Google Search Console documentation.

Link basics

Backlink

A backlink is a hyperlink on one website that points to a page on another website. Search engines treat backlinks as references between pages, and Google uses them as one signal of a page's importance. Backlinks are also called inbound links or incoming links. Read more on what backlinks are and how they work.

Referring domain

A referring domain is a unique website that links to your site at least once. One domain can send hundreds of backlinks yet still counts as one referring domain. SEO tools such as Ahrefs report referring domains separately because links from distinct sites show broader support than repeat links from one site. Read more on competitor backlink analysis.

Anchor text

Anchor text is the visible, clickable text of a hyperlink. It tells readers and search engines what the linked page is about. Common types include exact match, partial match, branded, naked URL and generic anchors such as "read more" or "click here". Read more on anchor text types and best practices.

Dofollow link

A dofollow link is a standard hyperlink with no nofollow, sponsored or ugc value in its rel attribute. Dofollow is an SEO label, not an actual HTML attribute. These links can pass ranking credit, so link builders usually target them for SEO value. Read more on high quality backlinks.

Nofollow

Nofollow is a rel attribute value, written rel="nofollow", that asks search engines not to pass ranking credit through a link. Google introduced it in 2005 to fight comment spam. Since 2019, Google treats nofollow as a hint rather than a strict directive.

Sponsored attribute

The sponsored attribute is a rel value, written rel="sponsored", that marks links created as part of advertisements, sponsorships or other paid agreements. Google introduced it in September 2019 alongside rel="ugc". Google treats it as a hint, and nofollow remains an accepted alternative for paid links.

UGC attribute

The UGC attribute is a rel value, written rel="ugc", that marks links inside user generated content such as forum posts and blog comments. Google introduced it in September 2019 alongside rel="sponsored". Site owners apply it to links their users place, not links they add themselves. Read more on community mentions service.

Link equity

Link equity is the ranking value a link passes from the linking page to the target page. SEOs also call it link juice. The amount depends on factors such as the linking page's authority, topical relevance, link placement and the rel attribute on the link. Read more on links from authoritative websites.

PageRank

PageRank is the algorithm Google uses to measure a page's importance from the quantity and quality of links pointing to it. Larry Page and Sergey Brin developed it at Stanford University in the late 1990s. Google still uses PageRank internally but no longer shows public scores. Read more on what link building is.

Link profile

A link profile is the complete set of backlinks pointing to a website. It covers referring domains, anchor text distribution, the dofollow and nofollow mix, link types and growth over time. SEO teams review the link profile to spot gaps against competitors and risky patterns. Read more on backlink monitoring.

Link types

Contextual link

A contextual link is a hyperlink placed inside the body text of an article, surrounded by copy on a related topic. It differs from links in sidebars, footers, navigation menus and author bios. The surrounding text gives search engines extra context about the linked page. Read more on contextual link building.

Guest post

A guest post is an article written by an outside author and published on another website. It usually carries a byline and a link back to the author's site. Link builders use guest posts to earn contextual backlinks. Our guest posts cost $62 at DR 10+ up to $388 at DR 60+. Read more on guest posting services by DR tier.

Niche edit

A niche edit is a backlink inserted into an existing, already indexed article on another website. It is also called a link insertion or curated link. The host page already has age and often traffic, so the link sits inside established content. Our niche edits start at $59. Read more on niche edit service.

Editorial link

An editorial link is a backlink that an editor or publisher places inside content on merit, because the linked page adds value for readers. Examples include citations in news articles, expert roundups and resource mentions. The publisher decides whether the link appears and where it sits. Read more on editorial link building.

Digital PR

Digital PR is the practice of earning coverage, brand mentions and backlinks from online news sites through newsworthy stories. Campaigns use original data, expert commentary or reactive news angles, then pitch journalists directly. Our digital PR campaigns start at $3,570 for 5 links. Read more on digital PR services.

HARO link

A HARO link is a backlink earned by answering a journalist's source request with an expert quote. The name comes from Help a Reporter Out, a source request service. Similar platforms include Qwoted and Featured. These links typically take 30 to 45 days because journalists choose which quotes to publish. Read more on HARO link building.

Local citation

A local citation is any online mention of a business's name, address and phone number. Citations appear on directories, maps and platforms such as Google Business Profile, Yelp, Bing Places and Apple Maps. Some citations include a link to the business website and others do not. Read more on local citation building.

NAP

NAP is an acronym for a business's name, address and phone number. Local SEO teams keep NAP details identical across the website, Google Business Profile and directory listings. Mismatched details, such as an old suite number or a different phone number, create conflicting signals about the business. Read more on NAP SEO and listing consistency.

Brand mention

A brand mention is any reference to a company, product or person on another website, with or without a hyperlink. A mention without a link is called an unlinked mention, and link builders often ask the publisher to turn it into a backlink. Mentions also shape how AI assistants describe a brand. Read more on brand mentions for AI search.

Metrics

Domain Rating

Domain Rating (DR) is an Ahrefs metric that scores the strength of a website's backlink profile on a 0 to 100 scale. The scale is logarithmic, so moving from DR 70 to 80 takes far more links than moving from DR 20 to 30. DR is not a Google ranking factor. Read more on SEO metrics guide.

Domain Authority

Domain Authority (DA) is a Moz metric that predicts how likely a domain is to rank in search results, scored from 1 to 100. Moz calculates it from its own link data, including linking root domains. Like Domain Rating, it is a third party estimate and not a Google metric.

URL Rating

URL Rating (UR) is an Ahrefs metric that scores the strength of a single page's backlink profile on a 0 to 100 scale. It works like Domain Rating but at page level. A brand new guest post page often shows a low UR, even on a high DR site.

Organic traffic

Organic traffic is the visits a website receives from unpaid search engine results. Ahrefs estimates it from a site's keyword rankings, search volumes and expected click rates. Link builders use this estimate to filter out sites with high DR but little real audience. We guarantee DR and Ahrefs traffic at placement. Read more on ways to increase blog traffic.

Topical relevance

Topical relevance is how closely the subject of a linking site or page matches the subject of the page it links to. A link from a SaaS marketing blog to a SaaS product page is topically relevant. Relevant links also send referral visitors who match your audience. Read more on how to choose link building services.

Outbound link ratio

Outbound link ratio is a vetting check. It compares the number of external sites a domain links to with the number of sites linking to it. A domain that links out far more than it receives links can signal a link selling site. It is a rule of thumb, not a standard metric.

Link velocity

Link velocity is the rate at which a website gains new referring domains or backlinks over a set period, such as a month. SEO teams compare it with competitors to set a realistic pace. Sudden spikes from unrelated sites are a common red flag in link audits. Read more on link building plan.

Process and outreach

Prospecting

Prospecting is the process of finding and qualifying websites to approach for a link. Link builders filter prospects by topical relevance, Domain Rating, organic traffic, outbound link ratio and editorial standards. A clean prospect list saves outreach time and removes link farms before any pitch goes out. Read more on how to do blogger outreach.

Outreach

Outreach is the practice of contacting site owners, editors or journalists to pitch content, a guest post or a link placement. Most outreach happens by email, with a personalized pitch and one or two follow ups. Our blogger outreach covers prospecting, pitching, writing and placement. Read more on blogger outreach service.

Link audit

A link audit is a structured review of every backlink pointing to a website. It flags spammy or manipulative links, anchor text over optimization, lost links worth reclaiming and gaps against competitors. The output is usually an action list, sometimes with a disavow file. Read more on backlink audit service.

Disavow file

A disavow file is a plain text file that lists URLs or domains you want Google to ignore when assessing links to your site. You upload it through the disavow links tool in Google Search Console. Google recommends it only when unnatural links have caused, or are likely to cause, a manual action.

White label link building

White label link building is a service where an agency buys links from a provider and resells them to clients under its own brand. The provider stays invisible, and reports carry no provider branding. Our reports are unbranded, so agencies can forward them directly to clients. Read more on white label link building.

Generative engine optimization

Generative engine optimization (GEO) is the practice of improving how often and how accurately a brand appears in answers from generative AI systems. Examples include ChatGPT, Perplexity, Gemini and Google AI Overviews. The term comes from a 2023 academic paper. Brand mentions, citations and clear entity data are common GEO inputs. Read more on AI SEO services.

Risk and policy

Toxic link

A toxic link is a backlink that SEO tools flag as spammy, manipulative or low quality. The label comes from third party tools, not from Google. Google says its systems can usually identify which links to trust without extra guidance, so a toxic score alone does not prove harm.

Link scheme

A link scheme is any attempt to manipulate search rankings through links that Google considers unnatural. Google's spam policies list examples such as paid links that pass ranking credit, excessive link exchanges, automated link creation and low quality directory links. Violations can lead to a manual action.

PBN

A PBN, short for private blog network, is a group of websites that one owner controls to link to a target site. Builders often use expired domains with existing backlinks. Google's spam policies treat links created to manipulate rankings as link spam, so PBNs carry penalty risk. Read more on PBN building service.

Link farm

A link farm is a group of websites that link to each other, or to paying sites, mainly to inflate link counts. The pages usually have thin content, unrelated topics and long lists of outbound links. Search engines devalue these links, and link builders exclude such sites during prospecting.

White hat link building

White hat link building is earning backlinks through methods that follow Google's spam policies. Examples include digital PR, editorial outreach, original research and broken link building. These links come from relevant sites where a publisher chooses to link because the content helps readers. Read more on white hat link building methods.

Gray hat link building

Gray hat link building is the use of tactics that sit between white hat and black hat methods. They are not always named in Google's spam policies, yet they bend the intent of those rules. Common examples include redirecting expired domains and small reciprocal link swaps. Their risk shifts as Google updates its policies.

Black hat link building

Black hat link building is the use of tactics that violate Google's spam policies to manipulate rankings. Examples include PBNs, link farms, automated link creation, links on hacked sites and hidden links. These tactics can lead to algorithmic devaluation or a manual action that removes rankings.

Manual action

A manual action is a penalty that a human reviewer at Google applies when a site violates Google's spam policies. Site owners see it in the Manual Actions report in Google Search Console. Unnatural links to your site is one manual action type. After fixing the issue, the owner files a reconsideration request.