Backlinks are incoming links to a website from other websites. They are important in search engine optimization (SEO) as they help search engines to understand how popular a website is, and to determine its relevance to certain keywords. The more high-quality backlinks a website has, the more likely it is to rank higher in search engine results pages. However, it is important to note that not all backlinks are created equal, and backlinks from reputable and relevant websites are more valuable than those from low-quality or irrelevant websites.