The definition
A backlink is a link on one website that points to a page on a different website. If a blog post on site A includes a link to a page on site B, that link is a backlink from site A's point of view of site B. That's the entire mechanism — everything else in this field is a variation on how that one link gets there and what it's worth once it exists.
Why backlinks matter to search engines
Search engines use backlinks as one signal — among many — of whether a page is worth showing for a given query. The reasoning, going back to the earliest search algorithms, is that a page other sites choose to link to is more likely to be useful than a page nobody links to. It's an imperfect signal and it's not the only one, but it's persisted for decades because it's genuinely hard to fake at scale without leaving a footprint.
The main types of backlinks
In practice, backlinks tend to fall into a few buckets, based on how the link came to exist:
- Earned/editorial links — another site links to your page voluntarily, because it's relevant or useful to their content.
- Guest post links — you (or a service on your behalf) write an article for another site, with a link included in the byline or body. See our guest posts vs PBN links comparison for how this differs from the next type.
- PBN links — a link placed on a site inside a network the placement provider owns and controls directly. See what a PBN is for the full explanation.
- Niche edits — a link added into an article that's already published, rather than a new one. See niche edits explained.
- Directory and profile links — links from business directories, forum profiles, and similar low-effort placements, generally considered weak on their own.
Why not all backlinks are equal
A link from a page that's topically relevant to yours, sits in genuine editorial content, and comes from a site with its own real audience carries more weight than a link from an unrelated directory page nobody reads. This is the reasoning behind everything in our quality backlink guide — relevance and context matter more than the raw fact that a link exists.
Where to go from here
If you're deciding which type of backlink actually fits a specific page you're trying to support, start with Guest Posts vs PBN Links, then Niche Edits Explained if timeline matters more than building a new page. If you want the full picture of how we select and place any of these, see our services page.