Fake Twitter accounts are accounts which are created at scale by bots, mainly to be resold as fake followers to brand or company accounts. For more details, see follower buying.
Some studies estimate the number of fake Twitter accounts to be in tens of millions.
Bots fill up profiles and sometimes animate an account through automatic publishing and following actions to make it real. Twitter’s captchas can be breaked through by effective bot programs or by humans paid to do it.
Fake accounts may also be used to produce fake retweets and for many Internet scams.