A backlink is simply a link from one website to another. Search engines like Google use backlink as a ranking signal because when one website links to another, it means they believe the content is noteworthy. High-quality backlinks can help to increase a site’s ranking position and visibility in search engine results (SEO).
However, there are dofollow links that are considered being bad or ‘toxic’. These links come from suspicious sites or are gained by breaking the search engine terms of service.