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For the greatest level of security, you should choose a different username for every single website, app, and platform you use. This prevents hackers from using a "cascade effect" attack once they gain access to one of your accounts. For ultimate security, utilize a password manager service that produces completely randomized usernames and passwords for you, then stores them in a secure vault. LastPass is one well-known option. In a "cascade effect" attack, a hacker uses info gained from one account to guess their way into other accounts. At the very least, use a different username for each category of accounts you have. For instance, use one username for social media, one for gaming, one for banking, and so on. Never use the same username and password combination, however. Having a single username per category makes it easier to remember them, and it also limits the potential damage of a "cascade effect" hack. You might think that using "JohnDWood" as a username isn't very revealing, but a dedicated hacker may be able to track down more detailed info about you just by knowing your name. That said, using your name is preferable in professional contexts, so limit your use of it to just that category. Combining the name you go by professionally with your profession is a good username combination. For instance, you might be "ReneeBlockAttorney," "ChefRodneyPeele," or "EdwardDSharpPlumber." In non-professional categories, don't use your full name or the name you go by. Adding numbers is an easy way to make a username unique, but don't give hackers any type of head start by giving away even a small amount of personal information. With just a few digits from a phone number or Social Security number (or similar government identification number), a skilled hacker may be able to figure out key info about you. Ideally, you shouldn't use the day or year you were born, either. And definitely don't use your entire birthdatefor example, "JohnSmith112483." Instead, use a number that's less revealing but still meaningful to you, like your age when you had your first kiss, your finishing time in your first marathon, or your grandparents' house number. For example, if your email address is "SteadyFreddy429@whmail.com," don't use "SteadyFreddy429" as your username for your gaming, banking, or other accounts. Keep your email name unique from any usernames. This is another simple way to make things a bit more difficult for hackers.
Choose as many different usernames as you can comfortably manage. Repeat usernames by category if you want fewer total usernames. Use your full name only as needed in a professional context. Don't use numbers from your address, phone number, or Social Security number. Don't use your email address as your username elsewhere.