In the context of online accounts or profiles, a special character is a symbol that is used to break up or enhance the format of a username. Examples of special characters include hyphens, underscores, periods, and @ symbols. The purpose of using special characters is often to create a unique username that is not already taken, or to make a username more visually appealing. However, when using special characters in a username, it's important to be aware of any restrictions or guidelines set by the website or platform in question, as some special characters may not be allowed or may cause issues with the account creation process.