Not the username, but the password is the most important part of an online account, and it is relatively easy to explain why. A username usually is displayed somewhere on the site the account is for. A Facebook wall post, a reply in an online forum or the writing of an article all show the username in one form or the other. And even if the username is not displayed openly it can be guessed more easily or often substituted with a user’s email address.
An account password on the other hand is not visible anywhere. Attackers with the right account password can usually get into an account easily, not so on the other hand if they only have the email or username of the user on the site.
Now that we have established that passwords are the most important part of a user’s online presence we need to find out how to make them as secure as possible.