What are characters in a username?

Related questions

1. What is password special character?
2. Do not use recurring character while choosing your password?
3. Can spyware steal credit card information?
4. Why is md5 not cryptographically secure?
5. Is md5 secure?
6. How long does it take to crack a 9 character password?
7. Can malware steal passwords?
8. How many passwords can a computer guess per second?
9. How long does it take to break 256 bit encryption?
10. What is 8 characters in a password?

Tags

1. #numbers
2. #comma
3. #cannot
4. #ampersand
5. #apostrophe
6. #brackets
7. #letters
8. #equals
9. #periods
10. #contain
11. #usernames
12. #period
13. #underscore