A hashtag is a word or phrase preceded by the "#" symbol, used primarily on social media platforms to categorize content. By adding a hashtag to a post, users can make it easier for others to find related content. For example, using the hashtag #Travel allows people interested in travel to discover posts about trips, destinations, and travel tips. Hashtags originated on Twitter in 2007 and have since become a common feature on various platforms like Instagram, Facebook, and TikTok. They help users engage in conversations, participate in trends, and promote events or campaigns by grouping similar posts together.