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how to save username on facebook
There is Facebook page with the Longest Username than any other:ThisIsTheLongestUsernameOnThisSocialNetworkForSure
A Facebook Username is for your "special" page URL. Say if you used "Waffles" as your username (if it was available) your Facebook URL would be "www.facebook.com/Waffles", also, you can use your username in place of your email when you sign in.
No
your email address.
willowsmith123
You must link it to Google or Twitter or Facebook and then Answers.com uses your Profile Picture.
It is the name that Facebook members choose to be known as on the site.
You can change username by following below steps given on website below. http://www.adkool.com/2009/06/grab-your-facebook-username-before.html
You can use the same username and password for Facebook for other sites but it is not recommended. If someone were to discover your username and password for one account, they would then have access to all the accounts where you used that same username and password.
Facebook account have unique facebook user profile and its link is created along with uniquie user id, this is facebook profile link. If user has spesified a username then the facebook profile link contains username instead of id.