A username is a unique identifier used to gain access to a computer, network, or online system. Usernames are also called an account name, user ID, login, or login ID. Users are either assigned a username, or they are allowed to create their own as long as it is unique and follows any specified parameters the system may have. It is a common practice for online systems to use an email address as a username.
Although it can be tempting to reuse a username, it is important to create unique usernames for different accounts. Reusing a username, especially if also reusing the password, can leave you more vulnerable to hackers and security breaches. A common example is a credential stuffing attack in which stolen account credentials consisting of usernames, email addresses, and passwords are used to gain unauthorized access to user accounts. It is alarming how much information can be found just by looking up someone’s reused username on the internet. Using a password manager can help you keep track of all your unique usernames and passwords, keeping your information more secure.