Backlinks ("incoming links") are all of the links that point to your website from other websites.When sorting search results, search engines orient themselves around a concept from real life: Recommendations! Therefore, if you are recommended often, that is typically advantageous for your ranking.
Search engines interpret a link to a website (backlink) as a recommendation of it. The more backlinks a website has, especially higher-quality backlinks, the further up this website will appear in the search results.
Good backlinks, for example, are generally those from websites based on similar topics.