About Twitter

• Twitter users can post tweets, updates of 140 characters or fewer at a time, to their profile wall. They can also "follow" the posts of other Twitter users. Some users have protected accounts, which disables their posts from being viewed or followed without the permission of the account holder. Many companies operate official Twitter accounts as a PR outlet.
  
  

Twitter Usernames

• Twitter usernames can contain letters, numbers and underscore symbols. They cannot contain spaces or other symbols, and are a maximum of 15 characters long. Users choose their username when registering for the site, and after their account is created, they can change their username from their account settings.
  
  

Verified Usernames

• Some Twitter accounts are considered "verified," indicating that the identity of the person associated with the account has been confirmed as legitimate by Twitter. Verified accounts display a sky-blue icon with a white check mark in their Twitter bio. Many celebrities own verified Twitter accounts. Some organizations, such as the United States Environmental Protection Agency, also operate verified Twitter accounts. Twitter continually adjusts its verification process, which is generally restricted to well-known personalities and organizations.
  
  

Twitter Usernames Outside of Twitter

• Some blogs and social networks accept sign-ins through Twitter instead of, or in addition to, their own verification system. Users with a Twitter account can then post on that blog as their Twitter identities without signing up for an account there. For many blogs, users can choose between using a Twitter username or a username from Twitter's rival social network, Facebook. Twitter accounts can also be linked to existing accounts on other social networks, although the user must explicitly allow the connection on both ends.
  
  

Twitter Bios

• As a Twitter user, you can associate a profile with your username, which is accessed from the Settings panel on the Twitter sidebar. This profile includes your homepage or blog website, location and bio. The bio is a short, descriptive phrase of 160 or fewer characters in which you post a description of yourself, your job and other identifying information. You can also choose an icon that appears at the top of each post.