External duplicate content refers to identical or substantially similar information found on multiple websites or online platforms that are not owned or controlled by the same entity. This can occur when content is copied or syndicated without proper attribution or permission, leading to duplicate versions of the same content appearing across the internet. External duplicate content can negatively impact search engine rankings and user experience, as it can confuse and frustrate readers who come across the same information multiple times. It is important for website owners and content creators to regularly monitor and address any instances of external duplicate content to maintain the uniqueness and credibility of their online presence.