A Backlink, also known as an inbound link or external link, is a link from one website to another. When another website links to your site, it creates a backlink. These links are a fundamental component of search engine algorithms, especially Google's.
Search engines view backlinks as 'votes of confidence' or endorsements. The more high-quality and relevant backlinks your site receives from authoritative domains, the more trustworthy and authoritative your site appears to search engines. This directly contributes to higher rankings in search results.
For example, if a reputable tech news site publishes an article about your new API and includes a link to your documentation page, that's a valuable backlink. It signals to search engines that your documentation is a credible resource. Conversely, links from low-quality or spammy sites can harm your SEO, making it crucial to focus on earning backlinks from relevant and authoritative sources.