The symbol "@" (at) is commonly used in digital communication, particularly in email addresses and social media. In an email, it separates the username from the domain name, such as in example@example.com. On platforms like Twitter and Instagram, it is used to tag or mention other users, allowing for direct interaction. In programming and coding, "@" can have various meanings depending on the context. For instance, in Python, it is used as a decorator to modify functions or methods. In HTML, it may appear in certain attributes, but its primary significance remains in communication and user interaction online.