A backlink is an inbound hyperlink from an external website that points to another website. Backlinks are a key component of search engine optimization (SEO), as search engines like Google use these links as a signal of a website’s relevance and trustworthiness. The more high-quality backlinks a website receives from reputable sources, the higher it can rank in search results. Backlinks can be acquired naturally through the dissemination of valuable content or through deliberate efforts like link-building campaigns. Not all backlinks are equal; links from spammy or low-quality sites can harm a website's SEO.