Backlink
Short definition
A backlink is a link from another website to yours, and search engines read it as a vote of confidence in your site.
A link from a trade publication, a local news site or a business partner acts like a vote for the search engine. The more reputable the linking site, the more weight it carries; a handful of links from trusted sites usually beats thousands from weak ones.
Bought links or links harvested in bulk from unrelated sites can be detected and penalised. A healthy backlink profile tends to come from genuine relationships, press coverage, guest articles and original content that people choose to cite.
A backlink is often confused with an internal link between two pages on the same site; an internal link only organises navigation within a site and carries no outside trust signal at all. Where a site's links come from can be checked in Google Search Console's links report, and a sudden, bulk jump there usually points to a purchased batch rather than links earned naturally.
Why it matters
When two pages are otherwise equal in quality, the backlink profile often decides which one ranks higher. Even strong content can sit behind competitors without links from sites the search engine already trusts.
Illustrative example
A spa chain gave an expert quote to a local health magazine, and the single resulting link outperformed months of chasing dozens of weaker ones.
