  Arguably one of the most important features of Twitter is the support for
"retweets" or messages re-posted verbatim by a user that were originated by
someone else. (This does not include modified tweets that sometimes are
referred to as retweets.) Despite the fact that retweets are routinely studied
and reported, many important questions remain about user motivation for their
use and their significance. In this paper we answer the question of what users
indicate when they retweet. We do so in a comprehensive fashion, by employing a
user survey, a study of user profiles, and a meta-analysis of over 100 research
publications from three related major conferences. Our findings indicate that
retweeting indicates not only interest in a message, but also trust in the
message and the originator, and agreement with the message contents. However,
the findings are significantly weaker for journalists, some of whom beg to
differ declaring so in their own user profiles. On the other hand, the
inclusion of hashtags strengthens the signal of agreement, especially when the
hashtags are related to politics. While in the past there have been additional
claims in the literature about possible reasons for retweeting, many of them
are not supported, especially given the technical changes introduced recently
by Twitter.
