Duplicate content refers to blocks of text or data that appear in more than one location on the internet. This can happen within a single website or across multiple sites. Search engines like Google may struggle to determine which version to rank, potentially leading to lower visibility for all instances of the content. Common causes of duplicate content include identical product descriptions on e-commerce sites, printer-friendly versions of pages, or content syndication. While not always harmful, excessive duplicate content can dilute a site's search engine optimization (SEO) efforts, making it important for website owners to manage and minimize it effectively.