Link building glossary

Backlinks

Backlinks are links on one website that point to a page on another website. Search engines treat them as references between pages: Google uses links to find new pages and as a signal of relevance, and the words in a link help it understand what the linked page is about.

Reviewed by Gareth Hoyle, Managing Director
Last reviewed 31 October 2026

How does Google use backlinks?

Google says it uses links as a signal when determining the relevancy of pages and to find new pages to crawl. PageRank, one of its original ranking systems, measures how pages link to each other, and Google says it is still part of its core ranking systems.

When Google changed how it handles nofollow in September 2019, it explained that links contain valuable information, such as how the words within links describe the content they point at. It can generally only crawl a link if it is an HTML a element with an href attribute, so links created only by script events may not count.

What makes a backlink valuable?

Not every link carries the same weight. The questions that matter are about the linking page and site, not the link count.

The linking site covers a topic related to yours
The linking site gets organic traffic and has links of its own
The link sits in the body of the content, not a footer or sidebar
The anchor text describes the page it points to
The link was given editorially, not paid for without a sponsored or nofollow attribute

Do backlinks still matter?

Ahrefs studied around 14 billion pages in its Content Explorer index in December 2023 and found 96.55% got no traffic from Google. Having no backlinks was one of the main reasons it gave. Of about 20 million pages with no referring domains, only 2,997 received more than 1,000 search visits a month. Ahrefs notes this is a correlation, not proof of cause, and that pages which get traffic without links are mostly on low-competition topics.

Example

A national gardening magazine links to a garden centre's guide with the anchor text 'how to plant bare-root roses'. That is one backlink from one referring domain. If the magazine links to the guide again from a second article, the garden centre has two backlinks but still one referring domain.