Twitter user names often signify businesses whose tweets are used for marketing and support. This usage creates the potential for conflicts with businesses already using the same or similar names. Twitter does not (yet) have a process for trademark owners to block user names and instead grants user names to the first person or company to apply for them. Registration on Twitter is free, so you may wish to register your company name as a Twitter user name to prevent others from doing so. It is a good idea to use the account periodically after registering, because inactive user names may be deleted.