A backlink is a link from one website to another. Backlinks play a key role in SEO. Search engines use backlinks to measure website authority. A high-quality backlink comes from a trusted site. You improve SEO rankings with more quality backlinks. You should focus on getting links from relevant websites. A backlink acts as a vote of confidence for your site. You should avoid backlinks from spammy or low-quality sites. Google values backlinks that come from unique domains. You can build backlinks through guest posts or partnerships. Backlinks remain one of the strongest ranking factors in SEO.