A backlink is a link from someone else's website to a page on yours. Search engines treat it as a vote: the more trusted and relevant the site casting it, the more it counts. Links are still among the strongest ranking signals Google has, which is exactly why buying them is against Google's rules and why earning them is slow.
Why links carry so much weight
Because they are hard to fake at scale and they come from outside your control. Anyone can write that they are the best plumber in town. Getting a supplier, a local paper and a trade body to link to you saying so is evidence of a different kind. Google's ranking systems guide still lists link analysis among the systems in use, and its founders built the company on the idea.
Which links count
Links from pages that are themselves indexed and visited, on sites relevant to your subject, placed in content rather than footers or comment sections, and not marked nofollow, sponsored or user-generated. One link from a relevant page that ranks is worth more than a hundred from a directory nobody reads.
Relevance matters more than size. A link from a wedding venue's suppliers page says more about a wedding fireworks business than a link from a national newspaper's unrelated listicle.
Which links are dangerous
Ones you paid for without marking them as sponsored, ones swapped in bulk, ones dropped into forum signatures and comment sections, and ones from networks of sites that exist only to link. Google's spam policies name all of these. Its systems mostly neutralise such links rather than penalise the site receiving them, but a pattern of them, especially with matching commercial anchor text, can attract a manual action.
The link-selling industry is built to sell to owners who do not know this. If someone emails offering guaranteed high-authority links for a fee, they are offering exactly the thing the rules describe.
How a small business earns them
From relationships you already have. Suppliers list stockists. Venues list recommended suppliers. Trade associations list members. Local organisations thank sponsors. Partners in adjacent trades, the electrician and the plumber, the venue and the caterer, recommend each other because they genuinely would. All of those are legitimate and most are one email away.
From things worth linking to. A price comparison that nobody else publishes, a guide that answers a question the whole trade gets asked, a dataset, a tool. Being the page that journalists and bloggers cite when they need a fact is the most durable link source there is.
The backlink gap report in the tracker lists the sites linking to your competitors and not to you. That is the shortlist.
Sources
Where this shows up in the tracker
Every term in this glossary is something the product actually measures or acts on. Plans start at £29 a month, with rank tracking, AI visibility, the daily AI readiness scan, security and domain health, Search Console, backlinks and audits on every one of them.
Related terms
PageRank
PageRank is the algorithm Google was founded on: a page's importance is estimated from the number and importance of the pages linking to it. Google still lists link analysis systems and PageRank among the systems it uses today. The public score was retired years ago, but the principle that links from trusted pages confer trust has never gone away.
Anchor text
Anchor text is the visible, clickable words of a link. Search engines read it as a description of the page being linked to, which makes it one of the clearest signals of what a page is about. Descriptive anchor text helps. Identical, keyword-stuffed anchor text across many links is one of the recognised marks of bought links.
Link spam
Link spam is Google's term for links created primarily to manipulate search rankings. Its spam policies name buying or selling links for ranking purposes, excessive link exchanges, automated link building, forum and comment links stuffed with keywords, and paid placements that do not block ranking credit. The consequence is usually that the links stop counting; in serious cases it is a manual action against the site that acquired them.
Domain rank
Domain authority, domain rating and domain rank are scores from zero to a hundred that SEO tools calculate from the links pointing at a website. Each tool has its own name and its own formula. Google has said repeatedly that it does not use any of them. They are useful for comparing sites against each other, and useless as a target in themselves.