Twitter hashtags are a way of categorising tweets and making them easily discoverable by other users interested in the same topic. They are words or phrases preceded by the # symbol, which turns them into clickable links. Hashtags are important for engagement because they allow businesses and individuals to connect with their audience, join relevant conversations, and increase the visibility of their tweets. Hashtags provide a way for users to search for and participate in Twitter chats, follow events, and keep up with trending topics.