Backlink: definition and what makes a quality link

What is a backlink?

A backlink, or inbound link, is a hyperlink published on a third-party site and pointing to a page on your site. It is also called an incoming link. A link between two pages of your own site is an internal link. It belongs to internal linking, not to backlinks.

Two measures are distinct. The number of backlinks counts every link. The number of referring domains counts the distinct sites that cite you. Practitioners mainly track the second indicator, which is harder to inflate artificially.

Earning backlinks in an organised way is called link building. Our link building strategy page covers the levers, the budget and the risk. This article focuses on the link itself and on what makes it a quality link.

What is a backlink made of?

A backlink fits into one line of HTML code. Each of its elements affects how Google interprets it.

<p>Read the <a href="https://www.example.com/migration-guide/" rel="sponsored">migration guide on the Example site</a> before the redesign.</p>

The destination URL

The href attribute contains the address of the target page. Google’s documentation on links (updated on December 10, 2025) is clear. Google only crawls a link if it is an <a> element with an href attribute. A link triggered only by JavaScript, with no href, is not crawled reliably.

The destination must return 200. And if it redirects? Google’s documentation on redirects (April 14, 2026) answers. A permanent redirect (301 or 308) acts as a signal to make the target the canonical page. Pointing directly to the final page is still cleaner.

The anchor

The anchor is the clickable text. Google recommends a descriptive anchor, reasonably short and relevant both to the source page and to the destination page. For a link placed on an image, Google uses the alt text as the anchor.

The rel attribute

The rel attribute qualifies the relationship. Google’s Qualify your outbound links page describes three values, which can be combined:

Value	Use intended by Google	Effect for the target site
None (a so-called “follow” link)	Default editorial link	Can pass on popularity
nofollow	Link you do not wish to endorse	As a general rule, not followed
sponsored	Advertising, paid partnership	As a general rule, not followed
ugc	User-generated content: comments, forums	As a general rule, not followed

A nofollow link is not useless for all that: it brings visits and brand visibility.

Why do backlinks matter to Google?

The idea goes back to the creation of the search engine. Sergey Brin and Lawrence Page describe PageRank in their founding 1998 paper. A page is considered important if other important pages cite it. The model is explained in our article on how PageRank is calculated.

The guide to Google’s ranking systems (December 10, 2025) confirms two points. The search engine analyses how pages link to each other to understand their topic and usefulness. And PageRank remains one of its core systems, heavily modified since 1998.

Google does, however, play down volume. In April 2024, Gary Illyes said that Google needed “very few links” to rank a page (Search Engine Journal). A backlink also serves discovery: Googlebot often finds a new page through an external link.

What is a quality backlink?

A good backlink is judged on the page that carries it, not only on the site. Here are the criteria to check, from the most blocking to the finest.

• The host page is indexed by Google. Otherwise, the link does not count.
• Its topic is close to the target page: an off-topic link passes on little.
• The link sits in the body text, in a paragraph on the same subject. Not in the footer or the sidebar.
• The page contains few other outbound links: the popularity passed on is shared between them.
• The link has no nofollow, sponsored or ugc attribute, if it is editorial.
• The anchor is natural and describes the target page, without mechanically repeating the same keyword.
• The target page is consistent with the anchor, returns 200 and does not redirect.
• The host page gets traffic and ranks itself. This is a sign that it matters to Google.

Placement matters because not all links on a page are equally likely to be clicked. This is the “reasonable surfer” hypothesis adopted by practitioners. An editorial link in the main content is worth more than a link repeated across a whole site. Google publishes no figures on weighting; it is a way of reasoning, not a measurement.

Which backlinks cause problems?

Google’s spam policies (updated on August 28, 2026) define “link spam”. These are links created mainly to manipulate rankings. Typical cases:

• links bought or obtained in exchange for a product, without a sponsored or nofollow attribute;
• excessive link exchanges between partner sites;
• links generated by automated programs;
• low-quality directories and bookmark sites;
• links hidden in widgets, or repeated in the footer of many sites;
• forum comments with optimised anchors.

Disavowing links is not a routine maintenance reflex. It is kept for situations involving a manual action or a known history of buying links. Our backlink audit method explains how to sort a link profile.

How can you see a site’s backlinks?

The free source is the Links report in Search Console. It lists the main sites and pages that point to yours. It is a sample, not a complete inventory. Our guide to Google Search Console explains how to export it.

Third-party tools (Ahrefs, Majestic, Semrush, Babbar, Haloscan) crawl the web with their own bots. Their figures differ from one tool to another and from Google’s. Compare trends, not absolute values.

1. Export the Search Console Links report every month and archive the file.
2. Spot the pages on your site that receive links but return a 404 error.
3. Redirect these old URLs to the equivalent page, as described in our article on the 301 redirect.
4. Compare your referring domains with those of two or three competitors on the same query.