  An identity of a user on an online social network (OSN) is defined by her
profile, content and network attributes. OSNs allow users to change their
online attributes with time, to reflect changes in their real-life. Temporal
changes in users' content and network attributes have been well studied in
literature, however little research has explored temporal changes in profile
attributes of online users. This work makes the first attempt to study changes
to a unique profile attribute of a user - username and on a popular OSN which
allows users to change usernames multiple times - Twitter. We collect, monitor
and analyze 8.7 million Twitter users at macroscopic level and 10,000 users at
microscopic level to understand username changing behavior. We find that around
10% of monitored Twitter users opt to change usernames for possible reasons
such as space gain, followers gain, and username promotion. Few users switch
back to any of their past usernames, however prefer recently dropped usernames
to switch back to. Users who change usernames are more active and popular than
users who don't. In-degree, activity and account creation year of users are
weakly correlated with their frequency of username change. We believe that past
usernames of a user and their associated benefits inferred from the past, can
help Twitter to suggest its users a set of suitable usernames to change to.
Past usernames may also help in other applications such as searching and
linking multiple OSN accounts of a user and correlating multiple Twitter
profiles to a single user.
